A job shop consists of three machines and two repairmen. The amount of time a machine works before breaking down is exponentially distributed with mean 10. If the amount of time it takes a single repairman to fix a machine is exponentially distributed with mean 8, then(a) what is the average number of machines not in use?(b) what proportion of time are both repairmen busy?

Answers

Answer 1

Answer:

Step-by-step explanation:

Let X(t) denote the number of machines breakdown at time t.

The givenn problem follows birth-death process with finite space

S={0, 1, 2, 3} with

[tex] \lambda_0=\frac{3}{10}, \mu_1=\frac{1}{8}\\\\ \lambda_1=\frac{2}{10}, \mu_2=\frac{2}{8}\\\\ \lambda_2=\frac{1}{10}, \mu_3=\frac{2}{8}[/tex]

The birth-death process having balance equations [tex]\lambda_sP_i=\mu_{s+1}P_{i+1},i=0,1,2[/tex]

since, state  rate at which leave = rate at which enter

            0      [tex]\lambda_0P_0=\mu_1P_1[/tex]

             1     [tex](\lambda_1+\mu_1)P_1= \mu_2P_2 + \lambda_0P_0[/tex]

             2   [tex](\lambda_2+\mu_2)P_2= \mu_3P_3 + \lambda_1P_1[/tex]

[tex]P_1=\frac{12}{5}P_0=P_0=\frac{5}{12}P_1\\\\P_2=\frac{48}{25}P_0=P_0=\frac{25}{48}P_2\\\\P_3=\frac{192}{250}P_0=P_0=\frac{250}{192}P_3[/tex]

Since [tex]\sum\limits^3_{i=0} {P_i=1}\\\\p_0=[1+\frac{5}{12}+\frac{48}{25}+\frac{192}{250}]^{-1}=\frac{250}{1522}[/tex]

a)

Average number not in use equals the mean of the stationary distribution [tex]P_1+2P_2+3P_3=\frac{2136}{751}[/tex]

b)

Proportion of time both repairmen are busy [tex]P_2+P_3=\frac{672}{1522}=\frac{336}{761}[/tex]

Answer 2
Final answer:

The average number of machines not in use is 0.5, and the repairmen are both busy 64% of the time. This has been found under the assumption of exponential distribution for both longevity of machines and repair time. The scenario represents a M/M/2 queue in operations research.

Explanation:

In this scenario, the life of the machines and the repair time are governed by exponential distributions. Exponential distribution is often used to model the amount of time until an event occurs, such as machine failure in this case.

(a) To find the average number of machines not in use, we need to consider the rate of machine breakdown and repair. A machine works an average of 10 hours before failure, which translates to a failure rate of 1/10. A single repairman can fix a machine in an average of 8 hours, meaning a rate of 1/8 per repairman, or 1/4 for two repairmen combined. As there are three machines, the average number of machines in use is the ratio of the arrival rate to the service rate: (1/10) / (1/4) = 2.5 machines. This implies that on average, 0.5 machines are not in use.

(b) Both repairmen will be busy when there are at least two machines that require fixing. The proportion of time in which this is the case is obtained by calculating the probability that the number of machines failed is two or more. This is a problem of queueing theory, in particular an M/M/2 queue. The formula for this probability is P(X >= k) = (1 - rho) * rho^(k) / (1 - rho^(c+1)), where rho = arrival rate / service rate, k = 2, and c = 2 (service channels). Substituting rho = 2.5, we obtain P(X >= 2) = 0.64, meaning that the repairmen are both busy 64% of the time.

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Related Questions

A yeast culture weighing 2 grams is removed from a refrigerator unit and is expected to grow at the rate of Upper W prime (t )equals0.1 e Superscript 0.1 t grams per hour at a higher controlled temperature. How much will the weight of the culture increase during the first 10 hours of​ growth? How much will the weight of the culture increase from the end of the 10th hour to the end of the 20th hour of​ growth?

Answers

Answer:

a) during the first 10 hours of growth the weight will increase 271.8% relative to the initial state ( or 2.718 g)

b) during the first 20 hours of growth the weight will increase  467.1 % relative to the initial state ( or 4.671 g)

Step-by-step explanation:

since the growing rate law is

W'(t) = 0.1 gr/hour * e^(0.1gr/hour* t)  , W'(t) [gr/hour]

and following mathematical conventions: W'(t)= dW/dt

then

dW/dt=0.1 e^(0.1t)

∫dW =∫0.1 e^(0.1t) dt

W = e^(0.1t) + C

at the beginning, (time t=0) the weight is W=2 grams .Therefore

2 g = e^(0.1 g/h*0) + C  → 2 g = 1 g + C → C = 1 g

then

W = e^(0.1t) + 1 g

at t= 10 hours

W = e^(0.1 g/h*10h) + 1 g = 3.718 g/h

therefore the weight will increase

ΔW = 3.718 g -  1 g = 2.718 g  or 271.8% relative to the initial state

for t=20 hours

W = e^(0.1 g/h*20h) + 1 g = 8.389 g/h

thus, the from t= 10 hours to t= 20 hours the weight will increase

ΔW =  8.389 g/h -  3.718 g = 4.671 g  or 467.1 %relative to the initial state

Final answer:

To find the growth of the yeast culture, we integrate the growth rate function over the respective intervals. For the first 10 hours, the yeast weight increases by roughly 1.718 grams. From the 10th to the 20th hour, it increases by approximately 4.671 grams.

Explanation:

To do this, we integrate the provided growth rate function over the given time intervals. Initially, the yeast culture weighs 2 grams and grows at the rate of W'(t) = 0.1e0.1t grams per hour.

Finding the Weight Increase During the First 10 Hours

To find the total growth over the first 10 hours, we calculate the integral of the growth rate from t = 0 to t = 10.

[tex]\[ \int_{0}^{10} 0.1e^{0.1t} dt = \left[ \frac{0.1}{0.1}e^{0.1t} \right]_{0}^{10} = \left[ e^{0.1t} \right]_{0}^{10} = e^{1} - e^{0} = e - 1 \][/tex]

Since e is approximately 2.718, this value becomes approximately 2.718 - 1, which equals 1.718 grams. Hence, during the first 10 hours, the yeast culture will increase by about 1.718 grams.

Weight Increase from the End of the 10th to the End of the 20th Hour

Again, we integrate the growth rate, but this time from t = 10 to t = 20.

[tex]\[ \int_{10}^{20} 0.1e^{0.1t} dt = \left[ e^{0.1t} \right]_{10}^{20} = e^{2} - e^{1} \][/tex]

Similar to the previous calculation, this yields e² - e which is approximately 7.389 - 2.718, resulting in an increase of approximately 4.671 grams.

Solve for x.
x + 8 = 12

Answers

Answer:

Step-by-step explanation:

move constant to the right and change the sign

X=12-8

X=4

X=12-8
X=4
X is equal to 4

HELP ASAP!! WILL MARK AS BRAINLIEST IF ANSWERED NOW!!!!

Sarah blends coffee for Tasti-Delight. She needs to prepare 170 lbs of blended coffee beans selling for $3.59 per pound. She plans to do this by blending together a high-quality bean costing $4.75 per pound and a cheaper bean at $2.00 per pound. To the nearest pound, find how much high-quality coffee bean and how much cheaper coffee bean she should blend.


She should blend ____ lbs of high-quality beans.


She should blend ____ lbs of cheaper beans.

Answers

Answer: She should blend 98 lbs of high-quality beans.

She should blend 72 lbs of cheaper beans

Step-by-step explanation:

Let x represent the number of pounds of high quality beans that she should blend.

Let y represent the number of pounds of cheaper beans that she should blend.

She needs to prepare 170 lbs of blended coffee beans. This means that

x + y = 170

She plans to do this by blending together a high-quality bean costing $4.75 per pound and a cheaper bean at $2.00 per pound. The blend would sell for $3.59 per pound. This means that the total cost of the blend would be 3.59×170 = $610.3. This means that

4.75x + 2y = 610.3 - - - - - - - - - -1

Substituting x = 170 - y into equation 1, it becomes

4.75(170 - y) + 2y = 610.3

807.5 - 4.75y + 2y = 610.3

- 4.75y + 2y = 610.3 - 807.5

- 2.75y = - 197.2

y = - 197.2/-2.75 = 71.9

y = 72 pounds

x = 170 - y = 170 - 71.9

x = 98.1

x = 98 pounds

9.2 x 10^8 is how many times the value of 2.3 x 10^2?

Answers

Answer:

4×10⁶

Step-by-step explanation:

Concept to know is that when you divide two numbers with the same base, you subtract their exponent.

So this problem could be split into 2 parts. The non power-of-ten numbers, and the power of tens numbers.

I divided 9.2/2.3 and got 4.

I then divided 10⁸/10² and got 10⁸⁻² = 10⁶.

Put it together and you get 4×10⁶

Number of times the value of 2.3×10² from 9.2×10⁸ is 4×10⁶.

What is scientific notation?

Scientific notation is a method for expressing a given quantity as a number having significant digits necessary for a specified degree of accuracy, multiplied by 10 to the appropriate power such as 1.56×10⁷.

The given numbers are 9.2×10⁸ and 2.3×10².

Now, number of times =9.2×10⁸/2.3×10²

= 4×[tex]10^{8-2}[/tex]

= 4×10⁶

Therefore, number of times the value of 2.3×10² from 9.2×10⁸ is 4×10⁶.

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It is claimed that automobiles are driven on average more than 20,000 kilometers per year. To test this claim, 100 randomly selected automobile owners are asked to keep a record of the kilometers they travel. Would you agree with this claim if the random sample showed an average of 23,500 kilometers and a standard deviation of 3900 kilometers? Use a P-value in your conclusion.

Answers

Answer:

[tex]t=\frac{23500-20000}{\frac{3900}{\sqrt{100}}}=8.974[/tex]      

[tex]p_v =P(t_{99}>8.974)=9.43x10^{-15}[/tex]  

If we compare the p value and the significance level given for example [tex]\alpha=0.05[/tex] we see that [tex]p_v<<\alpha[/tex] so we can conclude that we to reject the null hypothesis, and the actual mean is significantly higher than 20000.      

Step-by-step explanation:

1) Data given and notation      

[tex]\bar X=23500[/tex] represent the sample mean  

[tex]s=3900[/tex] represent the sample standard deviation      

[tex]n=100[/tex] sample size      

[tex]\mu_o =2000[/tex] represent the value that we want to test    

[tex]\alpha[/tex] represent the significance level for the hypothesis test.    

t would represent the statistic (variable of interest)      

[tex]p_v[/tex] represent the p value for the test (variable of interest)  

State the null and alternative hypotheses.      

We need to conduct a hypothesis in order to determine if the true mean is higher than 20000, the system of hypothesis would be:      

Null hypothesis:[tex]\mu \leq 2000[/tex]      

Alternative hypothesis:[tex]\mu > 2000[/tex]      

We don't know the population deviation, so for this case is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:      

[tex]t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}[/tex] (1)      

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".  

Calculate the statistic      

We can replace in formula (1) the info given like this:      

[tex]t=\frac{23500-20000}{\frac{3900}{\sqrt{100}}}=8.974[/tex]      

Calculate the P-value      

First we need to calculate the degrees of freedom given by:  

[tex]df=n-1=100-1=99[/tex]  

Since is a one-side upper test the p value would be:      

[tex]p_v =P(t_{99}>8.974)=9.43x10^{-15}[/tex]  

Conclusion      

If we compare the p value and the significance level given for example [tex]\alpha=0.05[/tex] we see that [tex]p_v<<\alpha[/tex] so we can conclude that we to reject the null hypothesis, and the actual mean is significantly higher than 20000.      

Final answer:

To evaluate the claim that automobiles are driven on average more than 20,000 kilometers per year, a one-sample t-test has to be conducted using the sample data. Based on the outcome of the test and the P-value generated, we can either reject or fail to reject the null hypothesis, hence determining whether to agree with the claim.

Explanation:

To determine whether you'd agree with the claim that automobiles are driven on average more than 20,000 kilometers per year based on the sample data, you would need to perform a hypothesis test. In this case, the null hypothesis (H0) would be that the average distance driven is equal to 20,000 kilometers. The alternative hypothesis (H1) would be that the average distance driven is more than 20,000 kilometers.

Your sample data indicates an average of 23,500 kilometers with a standard deviation of 3900 kilometers. To conduct the hypothesis test, you can use the formulas for a one-sample t-test because the population standard deviation is unknown. The P-value generated from the test will tell you whether to reject the null hypothesis.

If the P-value is less than the chosen significance level (commonly 0.05), you would reject the null hypothesis and conclude that automobiles are driven, on average, more than 20,000 kilometers per year. Otherwise, you would fail to reject the null hypothesis and could not conclusively agree with the claim. Without knowing the exact P-value derived from the test, it would be impossible to definitively agree or disagree with the claim based on the provided sample data.

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Compare Fractions
Compare. Write >,<, or =
1/5 1/15

Answers

Answer:

[tex] \frac{1}{5} \: and \: \frac{1}{15} [/tex]

Both of these must have similar denominators:

[tex] \frac{3}{15} \: and \: \frac{1}{15} \\ \frac{3}{15} \: i s \: \: more \: than \: \frac{1}{15} \\ \frac{3}{15} > \frac{1}{15} [/tex]

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Intelligent Muslim,

From Uzbekistan.

Akron Cinema sells an average of 500 tickets on Mondays, with a standard deviation of 50 tickets. If a simple random sample is taken of the mean amount of ticket sales from 30 Mondays in a year, what is the probability that the mean will be greater than 510?

Answers

Answer:

Step-by-step explanation:

Assuming the number of tickets sales from Mondays is normally distributed. the formula for normal distribution would be applied. It is expressed as

z = (x - u)/s

Where

x = ticket sales from monday

u = mean amount of ticket

s = standard deviation

From the information given,

u = 500 tickets

s = 50 tickets

We want to find the probability that the mean will be greater than 510. It is expressed as

P(x greater than 510) = 1 - P(x lesser than or equal to 510)

For x = 510

z = (510 - 500)/50 = 0.2

Looking at the normal distribution table, the probability corresponding to the z score is 0.9773

P(x greater than 510) = 1 - 0.9773 = 0.0227

Answer:

the correct answer is 0.1366

Step-by-step explanation:

A researcher determines thatχ2 = 3.76to test for significance for a phi correlation coefficient. What was the decision for this phi correlation test?a) Retain the null hypothesis.b) Reject the null hypothesis c) There is not enough information to answer this question.

Answers

Answer:

C. There is not enough information to answer this question

Step-by-step explanation:

Conclusion cannot be made whether to retain or reject the null hypothesis because the information given is not sufficient

Use the general slicing method to find the volume of the following solid.
The solid with a semicircular base of radius 11 whose cross sections perpendicular to the base and parallel to the diameter are squares. Place the semicircle on the xy-plane so that its diameter is on the x-axis and it is centered on the y-axis. Set up the integral that gives the volume of the solid. Use increasing limits of integration.

Answers

The integral that gives the volume of the solid is

∫[from -11 to 11] 4(121 - y²) dy, which equals 21395 cubic units.

We have,

To find the volume of the given solid using the general slicing method, we need to integrate the areas of the individual slices perpendicular to the base.

Each cross-section perpendicular to the base and parallel to the diameter is a square.

Let's set up the integral to calculate the volume:

First, let's consider a vertical slice at a distance "y" from the x-axis.

This slice would be a square with a side length "2x," where "x" is the horizontal distance from the y-axis to the rightmost edge of the square.

Since the diameter of the semicircle is on the x-axis and the semicircle is centred on the y-axis, we have a right triangle formed by the radius (11), the distance from the y-axis (x), and the distance from the x-axis (y).

Using the Pythagorean theorem: x² + y² = 11²

Solving for "x": x² = 11² - y²,

so x = √(121 - y²)

Now, the area of the square slice is (side length)² = (2x)² = 4x².

Since the limits of integration are determined by the range of y values, which go from -11 to 11 (the radius of the semicircle), the integral for the volume is:

V = ∫[from -11 to 11] 4x² dy

Substitute the expression for "x" in terms of "y":

V = ∫[from -11 to 11] 4(121 - y²) dy

Simplify:

V = 4 ∫[from -11 to 11] (484 - 4y²) dy

Integrate:

V = 4 [484y - (4/3)y³] | from -11 to 11

V = 4 [484(11) - (4/3)(11)³] - [484(-11) - (4/3)(-11)³]

V = 4 [5344 - (4/3) * 1331] + [5344 + (4/3) * 1331]

V = 14276 + 7119

   = 21395 cubic units

Thus,

The integral that gives the volume of the solid is

∫[from -11 to 11] 4(121 - y²) dy, which equals 21395 cubic units.

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Final answer:

The volume of the solid is found by integrating the area of the square cross sections, which are determined by the y-coordinate on the semicircle, along the x-axis. The equation for the volume integral is V = ∫ from -11 to 11 of 4(11² - x²) dx.

Explanation:

To find the volume of the solid, we need to integrate the area of the square cross sections along the length of the semicircle. The side length of each square is equal to the y-coordinate at that point (which ranges from -11 to 11). The general form of our semicircle in this position is [tex]y = \sqrt (11^2 - x^2),[/tex] where -11 ≤ x ≤ 11. The equation for the area of each square, then, is  [tex]A(x) = (2y)^2 = 4y^2 = 4(11^2 - x^2).[/tex]

Following the disk method for volumes of revolution, we need to integrate the cross-sectional area along the x-axis, from -11 to 11. So the total volume V is given by V = ∫ from -11 to 11 of A(x) dx = ∫ from -11 to 11 of 4(11² - x²) dx.

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Each lap around pavia park is 1 7/8 miles. Ellen rode her bike for 3 1/2 laps before leaving the park. How many total miles did ellen ride her bike in pavia park?

Answers

Answer:

Step-by-step explanation:

The distance of each lap around pavia park is 1 7/8 miles. Converting

1 7/8 miles to improper fraction, it becomes 15/8 miles.

Ellen rode her bike for 3 1/2 laps before leaving the park. Converting

3 1/2 laps to improper fraction, it becomes 7/2 laps.

The total number of miles that Ellen rode her bike in pavia park would be the product of the distance of each lap and the number of laps that he covered. It becomes

15/8 × 7/2 = 105/16 = 6.5626 miles

A plan for an executive travelers' club has been developed by an airline on the premise that 5% of its current customers would qualify for membership. A random sample of 500 customers yielded 45 who would qualify. (a) Using this data, test at level 0.01 the null hypothesis that the company's premise is correct against the alternative that it is not correct. State the appropriate null and alternative hypotheses. H0: p ≠ 0.05 Ha: p < 0.05 H0: p = 0.05 Ha: p > 0.05 H0: p = 0.05 Ha: p ≠ 0.05 H0: p ≠ 0.05 Ha: p = 0.05 Calculate the test statistic and determine the P-value. (Round your test statistic to two decimal places and your P-value to four decimal places.) z = P-value = State the conclusion in the problem context. Reject the null hypothesis. There is not sufficient evidence to conclude that the company's premise is incorrect. Do not reject the null hypothesis. There is not sufficient evidence to conclude that the company's premise is incorrect. Reject the null hypothesis. There is sufficient evidence to conclude that the company's premise is incorrect. Do not reject the null hypothesis. There is sufficient evidence to conclude that the company's premise is incorrect.

Answers

Answer:

Step-by-step explanation:

The Department of Transportation of the State of New York claimed that it takes an average of 200 minutes to travel by train from New York to Buffalo. To test if the average travel time differs from 200 minutes, a random sample of 40 trains was taken and the average time required to travel from New York to Buffalo was 188 minutes, with a standard deviation of 28 minutes. What is the p-value for this test?

Answers

Answer:

[tex]t=\frac{188-200}{\frac{28}{\sqrt{40}}}=-2.7105[/tex]    

[tex]p_v =2*P(t_{39}<-2.7105)=0.004967[/tex]    

Step-by-step explanation:

Data given and notation    

[tex]\bar X=188[/tex] represent the sample mean    

[tex]s=28[/tex] represent the sample standard deviation    

[tex]n=40[/tex] sample size    

[tex]\mu_o =2-0[/tex] represent the value that we want to test    

[tex]\alpha[/tex] represent the significance level for the hypothesis test.    

t would represent the statistic (variable of interest)    

[tex]p_v[/tex] represent the p value for the test (variable of interest)    

State the null and alternative hypotheses.    

We need to apply a two tailed tailed test.    

What are H0 and Ha for this study?    

Null hypothesis:  [tex]\mu = 200[/tex]    

Alternative hypothesis :[tex]\mu \neq 200[/tex]    

Compute the test statistic  

The statistic for this case is given by:    

[tex]t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}[/tex] (1)    

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".    

Calculate the statistic    

We can replace in formula (1) the info given like this:    

[tex]t=\frac{188-200}{\frac{28}{\sqrt{40}}}=-2.7105[/tex]    

Give the appropriate conclusion for the test  

First we need to find the degrees of freedom given by:

[tex]df=n-1=40-1=39[/tex]

Since is a two tailed test the p value would be:    

[tex]p_v =2*P(t_{39}<-2.7105)=0.004967[/tex]    

Conclusion    

If we compare the p value and a significance level assumed for example [tex]\alpha=0.05[/tex] we see that [tex]p_v<\alpha[/tex] so we can conclude that we have enough evidence to reject the null hypothesis, so we can concldue that the true mean is significantly different from 200 minutes at 5% of significance.    

With respect to the number of categories, k, when would a multinomial experiment be identical to a binomial experiment?

a. k = 2
b. k = 3
c. k = 4
d. k = 1

Answers

Answer:

Option A)  k = 2

Step-by-step explanation:

Multimonial Experiment

A multimonial experiment is an experiment with n repeated trials and each trial has a discrete number of possible outcomes.

Binomial Experiment

Binomial experiment is an experiment with n repeated trials and each trial has only two possible outcomes.

Thus, if k  represents the number of possible outcomes, then for k = 2, a multimonial experiment will become a binomial experiment.

Option A)  k = 2

A particle is moving with the given data. Find the position of the particle. v(t) = 1.5√t , s(4) = 14.

Answers

Final answer:

The particle's position, represented by s(t), is found from its velocity v(t) using integration. The function of the velocity is rewritten, integrated, and a constant of integration is found using the given initial condition.

Explanation:

The problem given involves a particle moving with a certain velocity function, v(t) = 1.5√t, and an initial position at t = 4, that is, s(4) = 14. The problem asks for the position of the particle, which is often represented by a displacement or position function, denoted commonly as s(t).

To solve this problem, we need to use the fundamental relationship between velocity and position, which states that velocity is the rate of change of position with respect to time. This relationship implies that to find the position function from the velocity function, we need to find an antiderivative or integral of the velocity function.

Take the velocity function, v(t) = 1.5√t. To find the antiderivative, we need to write the square root in exponential form, making the function become v(t) = 1.5t0.5.The rule of integration ∫t^n dt = (t^(n+1))/(n+1) + C is used. To find the antiderivative of the function, the exponent is increased by 1 and the result is divided by the new exponent.  The result would be s(t) = t^1.5/(1.5) + C.As per the given data, we know that s(4) = 14. Substitute these values to solve for C: 14 = (4)^1.5/1.5 + C. Solve for C to complete the position function.

By following this step-by-step method, we can determine the position of the particle based on the given information.

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The position of the particle is given by the function s(t) = t^(3/2) + 6.

To find the position of the particle, we need to integrate the given velocity function, [tex]v(t)=1.5\sqrt{t}[/tex].

First, let's find the indefinite integral of v(t):

[tex]\int\limits {v(t)} \, dt = \int\limits {1.5\sqrt{t} } \, dt[/tex]

Rewrite the square root as a power:

[tex]=\int\limits {1.5t^{\frac{1}{2} } \, dt[/tex]

Apply the power rule of integration:

[tex]=\frac{1.5t^{(\frac{1}{2}+1 )} }{\frac{1}{2} +1} + C[/tex]

[tex]= 1.5*(\frac{2}{3} )t^{\frac{3}{2}}+C[/tex]

[tex]=t^\frac{3}{2} +C[/tex]

Now we use the initial condition s(4) = 14 to solve for C:

[tex]s(t)=t^\frac{3}{2} +C[/tex][tex]s(4)=(4)^\frac{3}{2} +C=14[/tex][tex]4^\frac{3}{2} = (\sqrt{4} )^3 = 2^3=8[/tex]

Therefore:

8 + C = 14C = 14 - 8C = 6

So the position function is:

[tex]s(t)=t^\frac{3}{2} +6[/tex]

A recent study compared the time spent together by single- and dual-earner couples. According to the records kept by the wives during the study, the mean amount of time spent together watching television among the single-earner couples was 61 minutes per day, with a standard deviation of 15.5 minutes. For the dual-earner couples, the mean number of minutes spent watching television was 48.4 minutes, with a standard deviation of 18.1 minutes. At the 0.01 significance level, can we conclude that the single-earner couples on average spend more time watching television together?

Answers

We can see here that at the 0.01 significance level, we can actually conclude that the single-earner couples on average spend more time watching television together.

How we arrived at the solution?

To determine whether we can conclude that single-earner couples spend more time watching television together on average than dual-earner couples, we can perform a hypothesis test.

The null hypothesis (H₀) assumes that there is no difference in the mean time spent watching television between the two groups, while the alternative hypothesis (H₁) suggests that single-earner couples spend more time together watching television.

Let's set up the hypotheses:

Null Hypothesis (H₀): μ₁ ≤ μ₂ (The mean time spent together watching television for single-earner couples is less than or equal to the mean time for dual-earner couples.)

Alternative Hypothesis (H₁): μ₁ > μ₂ (The mean time spent together watching television for single-earner couples is greater than the mean time for dual-earner couples.)

Where:

μ₁ = population mean time spent watching television for single-earner couples

μ₂ = population mean time spent watching television for dual-earner couples

Next, we will use a two-sample t-test to test the hypotheses. Since we are trying to determine if single-earner couples spend more time watching television, this will be a one-tailed t-test.

Given the sample means, sample standard deviations, and sample sizes, we can calculate the t-statistic and compare it to the critical t-value at the 0.01 significance level (α = 0.01) with degrees of freedom d f = n₁ + n₂ - 2, where n₁ and n₂ are the sample sizes of single-earner and dual-earner couples, respectively.

Let's assume the sample sizes are n₁ = n₂ = 30 (the actual sample sizes from the study are not given in the question, but this is just for demonstration purposes).

Now, we can calculate the t-statistic:

t = (x₁ - x₂) / √((s₁²/n₁) + ([tex]s_{2}[/tex]² /n₂))

where:

x₁ = sample mean time for single-earner couples

x₂ = sample mean time for dual-earner couples

s₁ = sample standard deviation for single-earner couples

[tex]s_{2}[/tex] = sample standard deviation for dual-earner couples

n₁ = sample size for single-earner couples

n₂ = sample size for dual-earner couples

Using the provided values:

x₁ = 61 minutes

x₂ = 48.4 minutes

s₁ = 15.5 minutes

= 18.1 minutes

n₁ = n₂ = 30 (sample sizes assumed for demonstration)

Calculating the t-statistic:

t = (61 - 48.4) / √((15.5²/30) + (18.1²/30))

t ≈ 4.083

Next, we need to find the critical t-value from the t-distribution table at α = 0.01 significance level and df = 30 + 30 - 2 = 58 (degrees of freedom).

The critical t-value at α = 0.01 with d  f = 58 is approximately 2.660.

Since the calculated t-statistic (4.083) is greater than the critical t-value (2.660), we reject the null hypothesis (H₀).

Therefore, at the 0.01 significance level, we can conclude that single-earner couples, on average, spend more time watching television together than dual-earner couples based on the data provided in the study.

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To determine whether single-earner couples spend more time watching television together than dual-earner couples, an independent samples t-test must be conducted at the 0.01 significance level. Using the provided means and standard deviations, we would calculate a t-statistic and compare it against critical values to either reject the null or fail to reject it.

The question asks whether single-earner couples spend more time watching television together than dual-earner couples, based on a study with provided mean values and standard deviations for both groups. To determine if there is a statistically significant difference between the two means, we would conduct a hypothesis test, specifically an independent samples t-test, at the 0.01 significance level. The null hypothesis (0) would state that there is no difference in the mean television watching times between the groups, while the alternative hypothesis (A) would claim that there is a difference, specifically that single-earner couples watch more television.

Given that the mean time spent watching television for single-earner couples is 61 minutes with a standard deviation of 15.5 minutes, and for dual-earner couples it is 48.4 minutes with a standard deviation of 18.1 minutes, we would calculate the t-statistic and compare it against the t-distribution critical values for the given degrees of freedom. If the calculated t-statistic exceeds the critical value for a one-tailed test at the 0.01 level, we would reject the null hypothesis and conclude that there is a significant difference, supporting the claim that single-earner couples spend more time watching television together.

We're testing the hypothesis that the average boy walks at 18 months of age (H0: p = 18). We assume that the ages at which boys walk is approximately normally distributed with a standard deviation of 2.5 months. A random sample of 25 boys has a mean of 19.2 months. Which of the following statements are correct?

I. This finding is significant for a two-tailed test at .05.
II. This finding is significant for a two-tailed test at .01.
III. This finding is significant for a one-tailed test at .01.

a. I only
b. II only
c. III only
d. II and III only
e. I and III only

Answers

Answer:

II. This finding is significant for a two-tailed test at .01.

III. This finding is significant for a one-tailed test at .01.

d. II and III only

Step-by-step explanation:

1) Data given and notation    

[tex]\bar X=19.2[/tex] represent the battery life sample mean    

[tex]\sigma=2.5[/tex] represent the population standard deviation    

[tex]n=25[/tex] sample size    

[tex]\mu_o =18[/tex] represent the value that we want to test    

[tex]\alpha[/tex] represent the significance level for the hypothesis test.    

t would represent the statistic (variable of interest)    

[tex]p_v[/tex] represent the p value for the test (variable of interest)    

2) State the null and alternative hypotheses.    

We need to conduct a hypothesis in order to check if the mean battery life is equal to 18 or not for parta I and II:    

Null hypothesis:[tex]\mu = 18[/tex]    

Alternative hypothesis:[tex]\mu \neq 18[/tex]    

And for part III we have a one tailed test with the following hypothesis:

Null hypothesis:[tex]\mu \leq 18[/tex]    

Alternative hypothesis:[tex]\mu > 18[/tex]  

Since we know the population deviation, is better apply a z test to compare the actual mean to the reference value, and the statistic is given by:    

[tex]z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}[/tex] (1)    

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".    

3) Calculate the statistic    

We can replace in formula (1) the info given like this:    

[tex]z=\frac{19.2-18}{\frac{2.5}{\sqrt{25}}}=2.4[/tex]    

4) P-value    

First we need to calculate the degrees of freedom given by:  

[tex]df=n-1=25-1=24[/tex]  

Since is a two tailed test for parts I and II, the p value would be:    

[tex]p_v =2*P(t_{(24)}>2.4)=0.0245[/tex]

And for part III since we have a one right tailed test the p value is:

[tex]p_v =P(t_{(24)}>2.4)=0.0122[/tex]

5) Conclusion    

I. This finding is significant for a two-tailed test at .05.

Since the [tex]p_v <\alpha[/tex]. We reject the null hypothesis so we don't have a significant result. FALSE

II. This finding is significant for a two-tailed test at .01.

Since the [tex]p_v >\alpha[/tex]. We FAIL to reject the null hypothesis so we have a significant result. TRUE.

III. This finding is significant for a one-tailed test at .01.

Since the [tex]p_v >\alpha[/tex]. We FAIL to reject the null hypothesis so we have a significant result. TRUE.

So then the correct options is:

d. II and III only

Answer:

E. I and III only

Step-by-step explanation:

I. .05

III. one-tailed at .01

Which one of the following test and evaluation (T&E) products is required at Milestone B? (DAU Course ACQ 202)

A. Waiver of Military Equipment Program Description

B. Operational Assessment

C. Identification of LRIP Quantities

D. No T&E products are required at MS B

Answers

The test and evaluation (T&E) product that is required will be

C. Identification of LRIP Quantities.

It should be noted that a Test and Evaluation Master Plan is used as the planning and management tool for the test activities.

On the other hand, Milestone B is assumed as the official start of a program. It's a MDA led review at the final phase of the Technology Maturation and Risk Reduction.

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Among the options provided, the correct answer is B. Operational Assessment, as it is a required T&E product at Milestone B.

In the Department of Defense Acquisition Process, Milestone B represents a significant point in the acquisition lifecycle where programs are reviewed and approved for entry into the Engineering and Manufacturing Development (EMD) phase.

At Milestone B, the primary focus is on ensuring that the program is mature enough to proceed into EMD with an acceptable level of risk and that adequate planning has taken place.

Among the options provided:

A. Waiver of Military Equipment Program Description: This document is typically not required at Milestone B. It may be relevant in other phases but not a direct requirement at this milestone.

B. Operational Assessment: Operational Assessment (OA) is a crucial T&E product at Milestone B. It assesses the operational effectiveness and suitability of the system under realistic operational conditions, helping to determine whether the system is suitable for further development and production.

C. Identification of LRIP Quantities: The identification of Low-Rate Initial Production (LRIP) quantities is also an important consideration at Milestone B. Decisions about LRIP quantities are critical for moving forward with limited production to further test and refine the system.

D. No T&E products are required at MS B: This statement is not accurate. Milestone B does require specific T&E products, such as the Operational Assessment and considerations related to LRIP quantities, as mentioned above.

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Suppose that n(U) = 200, n(A) = 165, n(B) = 95, and n( A ∩ B ) = 80. Find n( A c ∪ B ).

a. 85
b. 95
c. 15
d. 35
e. 115
f. None of the above.

Answers

Answer:

d) 35

Step-by-step explanation:

Consider the venn diagram attached below

Given

n(U) = 200

n(A) = 165

n(B) = 95

n(A ∩ B ) = 80

n([tex]A^{c}[/tex] ∪ B) =?

Using

n(A  ∪ B) = n(A) + n(b) - n(A ∩)B

For [tex]A^{c}[/tex]

[tex]n(A^{c}\cup B) = n(A^{C})+ n(B)-n(A^{c}\cap B)---(1)\\n(A^{c})=U-A\\n(A^{c})=n(U)-n(A)\\A^{c}\cap B=B\\n(A^{c}\cap B) =n(B)\\[/tex]

Then (1) becomes

[tex]n(A^{c}\cup B) = n(U)-n(A)+ n(B)-n(B)\\n(A^{c}\cup B)=200-165+95-95\\n(A^{c}\cup B)=35[/tex]

The number of customers that enter a store during one day in an example of:
-a continuous random variable
-a discrete random variable
-either a continuous or a discrete random variable, depending on the gender of the customers

Answers

Answer:

-a discrete random variable

Step-by-step explanation:

The number of customers that enter a store can be 0,1,2,...,100,1000,etc...

If cannot be a decimal number, for example, 0.5. So it is a discrete random variable.

The correct answer is:

-a discrete random variable

The U.S. Bureau of Labor Statistics reports that 11.3% of U.S. workers belong to unions (BLS website, January 2014). Suppose a sample of 400 U.S. workers is collected in 2014 to determine whether union efforts to organize have increased union membership. a. Formulate the hypotheses that can be used to determine whether union membership increased in 2014. H 0: p H a: p b. If the sample results show that 52 of the workers belonged to unions, what is the p-value for your hypothesis test (to 4 decimals)? c. At = .05, what is your conclusion?

Answers

Answer:

There is not enough evidence to support the claim that union membership increased.

Step-by-step explanation:

We are given the following in the question:

Sample size, n = 400

p = 11.3% = 0.113

Alpha, α = 0.05

Number of women belonging to union , x = 52

First, we design the null and the alternate hypothesis

[tex]H_{0}: p = 0.113\\H_A: p > 0.113[/tex]

The null hypothesis sates that 11.3% of U.S. workers belong to union and the alternate hypothesis states that there is a increase in union membership.

Formula:

[tex]\hat{p} = \dfrac{x}{n} = \dfrac{52}{400} = 0.13[/tex]

[tex]z = \dfrac{\hat{p}-p}{\sqrt{\dfrac{p(1-p)}{n}}}[/tex]

Putting the values, we get,

[tex]z = \displaystyle\frac{0.13-0.113}{\sqrt{\frac{0.113(1-0.113)}{400}}} = 1.073[/tex]

now, we calculate the p-value from the table.

P-value = 0.141636

Since the p-value is greater than the significance level, we fail to reject the null hypothesis and accept the null hypothesis.

Thus, there is not enough evidence to support the claim that union membership increased.

The evidence isn't sufficient enough to support the claim that union membership increased.

What is p-value?

This is a statistical measurement used to validate a hypothesis against observed data.

Parameters

Sample size, n = 400

p = 11.3% = 0.113

Alpha, α = 0.05

Number of women belonging to union   = 52

H₀ : p = 0.113

Hₐ : p  > 0.113

This means 11.3% of U.S. workers belong to union and there was an increase.

p = x / n

z = p - p /(( √p(1-p) /n

 = 53/400 = 0.13

z = p - p /(( √p(1 - p) /n)).

Substitute the values into the equation.

z = 0.13 - 0.113 / ((√0.113(1-0.113)/400)) = 1.073

P-value = 0.141636 from the table which is greater than the significance level, hence we accept the null hypothesis.

The evidence is therefore not sufficient enough to support the claim that union membership increased.

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Determine whether the variable is qualitative or quantitative.
Street name of address
is the variable qualitative or quantitative?

A. The variable is quantitative because it is an attribute characteristic
B. The variable is qualitative because it is a numerical measure
C. The variable is quantitative because it is a numerical measure
D. The variable is qualitative because it is an attribute characteristic.

Answers

Answer:

D. The variable is qualitative because it is an attribute characteristic.

Step-by-step explanation:

In an address, the street name is an attribute of the address.

An attribute is a qualitative variable.

So the correct answer is:

D. The variable is qualitative because it is an attribute characteristic.

The variable is qualitative because it is an attribute characteristic.

Option D is correct

A qualitative variable is a variable whose values are varied by attributes or characteristics. Examples are hair color, course done in school, gender, etc.

A quantitative variable is a variable whose values are varied by actual measurement. Examples are number of odd numbers, number of students in a class, the population of a country, etc.

The description of the given variable is:

Street name of address

This description represents the attribute or characteristic of a location. Therefore, it is a qualitative variable

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A particular poll tracks daily the percentage of Americans who approve or disapprove of the performance by President 1. Daily results are based on random telephone interviews with approximately 1300 national adults. The poll reports that 41​% of adults approve of President 1. The same poll reported an approval rating of 42​% for President 2. A news anchor remarks that​ "President 1​ doesn't even get as much approval as President 2​ did." Is there evidence that this difference is​ real? State and test the appropriate hypotheses.

Answers

Answer:

Null hypothesis:[tex]p_{1} = p_{2}[/tex]  

Alternative hypothesis:[tex]p_{1} \neq p_{2}[/tex]

[tex]z=\frac{0.41-0.43}{\sqrt{0.42(1-0.42)(\frac{1}{1300}+\frac{1}{1300})}}=-1.033[/tex]    

[tex]p_v =2*P(Z<-1.033)=0.302[/tex]  

So the p value is a very high value and using any significance level for example [tex]\alpha=0.05, 0,1,0.15[/tex] always [tex]p_v>\alpha[/tex] so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can say the the proportion 1 is not significantly different from the proportion 2.  

Step-by-step explanation:

1) Data given and notation  

n = 1300 sample size selected

[tex]p_{1}=0.41[/tex] represent the proportion of adults approve of President1.

[tex]p_{2}=0.42[/tex] represent the proportion of adults approve of President2.

z would represent the statistic (variable of interest)  

[tex]p_v[/tex] represent the value for the test (variable of interest)  

2) Concepts and formulas to use  

We need to conduct a hypothesis in order to check if the proportion 1 is different from proportion 2  , the system of hypothesis would be:  

Null hypothesis:[tex]p_{1} = p_{2}[/tex]  

Alternative hypothesis:[tex]p_{1} \neq p_{2}[/tex]  

We need to apply a z test to compare proportions, and the statistic is given by:  

[tex]z=\frac{p_{1}-p_{2}}{\sqrt{\hat p (1-\hat p)(\frac{1}{n_{1}}+\frac{1}{n_{2}})}}[/tex]   (1)  

Where [tex]\hat p=\frac{X_{1}+X_{2}}{n_{1}+n_{2}}=\frac{0.41+0.43}{2}=0.42[/tex]  

3) Calculate the statistic  

Replacing in formula (1) the values obtained we got this:  

[tex]z=\frac{0.41-0.43}{\sqrt{0.42(1-0.42)(\frac{1}{1300}+\frac{1}{1300})}}=-1.033[/tex]    

4) Statistical decision

For this case we don't have a significance level provided [tex]\alpha[/tex], but we can calculate the p value for this test.    

Since is a two sided test the p value would be:  

[tex]p_v =2*P(Z<-1.033)=0.302[/tex]  

So the p value is a very high value and using any significance level for example [tex]\alpha=0.05, 0,1,0.15[/tex] always [tex]p_v>\alpha[/tex] so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can say the the proportion 1 is not significantly different from the proportion 2.  

A factory produces plate glass with a mean thickness of 4 mm and a standard deviation of 1.1 mm. A simple random sample of 100 sheets of glass is to be measured, and the mean thickness of the 100 sheets is to be computed. What is the probability that the average thickness of the 100 sheets is less than 3.83 mm? . Round your answers to 5 decimal places.

Answers

Answer:

[tex]P(\bar X<3.83)=0.06117[/tex]

Step-by-step explanation:

1) Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".  

Let X the random variable that represent the thickness of a population, and for this case we know the distribution for X is given by:

[tex]X \sim N(4,1.1)[/tex]  

Where [tex]\mu=4[/tex] and [tex]\sigma=1.1[/tex]

And let [tex]\bar X[/tex] represent the sample mean, the distribution for the sample mean is given by:

[tex]\bar X \sim N(\mu,\frac{\sigma}{\sqrt{n}})[/tex]

On this case  [tex]\bar X \sim N(4,\frac{1.1}{\sqrt{100}})[/tex]

2) Solution to the problem

We are interested on this probability

[tex]P(\bar X<3.83)[/tex]

And the best way to solve this problem is using the normal standard distribution and the z score given by:

[tex]z=\frac{x-\mu}{\frac{\sigma}{\sqrt{n}}}[/tex]

If we apply this formula to our probability we got this:

[tex]P(\bar X<3.83)=P(\frac{X-\mu}{\frac{\sigma}{\sqrt{n}}}<\frac{3.83-\mu}{\frac{\sigma}{\sqrt{n}}})[/tex]

[tex]=P(Z<\frac{3.83-4}{\frac{1.1}{\sqrt{100}}})=P(Z<-1.545)[/tex]

And in order to find this probability we can find tables for the normal standard distribution, excel or a calculator.  

[tex]P(Z<-1.545)=0.06117[/tex]

And the excel formula to calculate it would be:

"=NORM.DIST(-1.545,0,1,TRUE)"

The probability is 49.20%

The z score shows by how many standard deviations the raw score is above or below the mean. The z score is given by:

[tex]z=\frac{x-\mu}{\sigma} \\\\where\ x=raw\ score,\mu=mean,\sigma=standard\ deviation.\\\\For\ a\ sample\ size\ n:\\\\z=\frac{x-\mu}{\sigma/\sqrt{n} }[/tex]

Given that n = 100, μ = 4 mm, σ = 1.1 mm

For x < 3.83 mm:

[tex]z=\frac{x-\mu}{\sigma/\sqrt{n} } \\\\z=\frac{3.83-4}{1.1/\sqrt{100} } =-0.0187[/tex]

P(x < 3.83) = P(z < -0.0187) = 0.4920 = 49.20%

From the normal distribution table, the probability that the average thickness of the 100 sheets is less than 3.83 mm is 49.20%

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13 gallons of gas cost $24.31 what is the cost per gallon

Answers

Answer:

The cost per gallon is US$ 1.87

Step-by-step explanation:

1. Let's review the information provided to us to answer the question correctly:

Number of gallons of gas = 13

Cost of the gallons of gas = US$ 24.31

2. What is the cost per gallon?

Cost per gallon = Cost of the gallons of gas/Number of gallons of gas

Replacing with the real values, we have:

Cost per gallon = 24.31/13

Cost per gallon = 1.87

The cost per gallon is US$ 1.87

Tell whether the number is evenly divisible by 2, 3, 4, or 6.

6) 44

7) 38

8) 726

9) 2112

10) 1221

Answers

Answer:

Step-by-step explanation:

If a number is evenly divisible by another number, it means that the number divides it completely without a remainder.

6) 44 is evenly divisible by 2 and 4. 44 divided by 3 and 6 would have remainders.

7) 38 is evenly divisible by 2. There would be remainders if 38 divides 3, 4 or 6

8) 726 is evenly divisible by 2, 3 and 6. It is not evenly divisible by 4

9) 2112 is evenly divisible by 2, 3 4 and 6

10) 1221 is evenly divisible by 3. It is not evenly divisible by 2 4 and 6

Find a particular solution to the nonhomogeneous differential equation y??+4y?+5y=?10x+e^(?x).

yp=
Find the most general solution to the associated homogeneous differential equation. Use c1 and c2 in your answer to denote arbitrary constants, and enter them as c1 and c2.

yh=
Find the most general solution to the original nonhomogeneous differential equation. Use c1 and c2 in your answer to denote arbitrary constants.

y=

Answers

Final answer:

The solution is a three-step process. First, solve the characteristic equation and determine the homogeneous solution. Second, use the method of undetermined coefficients to find the particular solution. Finally, the general solution to the nonhomogeneous differential equation equals the sum of the homogeneous solution and the particular solution.

Explanation:

To solve this, we'll need to go through three stages: solving the homogeneous equation, finding the particular solution, and finally combining these to form the general solution.

Step 1: The associated homogeneous equation is y'' + 4y' + 5y = 0. The general solution to this homogeneous equation can be obtained by solving the characteristic quadratic equation r^2 + 4r + 5 = 0. You will find that the roots are complex, and the general solution for the homogeneous differential equation would be in the form yh = c1*e^(-2x)cos(x)+c2*e^(-2x)sin(x).

Step 2: The particular solution of the nonhomogeneous differential equation can be obtained using the method of undetermined coefficients or the method of variation of parameters. For this case, we will use the method of undetermined coefficients. You will eventually find after performing these methods that the particular solution yp is of the form yp = Ax + Be^(?x), where A and B are constants which can be calculated.

Step 3: Finally, the general solution to the nonhomogeneous differential equation we are trying to solve is simply the sum of the general solution from Step 1 (the homogeneous solution) and the particular solution from Step 2. This would yield a solution y = c1*e^(-2x)cos(x) + c2*e^(-2x)sin(x) + Ax + Be^(?x).

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Final answer:

The solution to the homogeneous differential equation is yh=c1e^-2x cos(x) + c2e^-2x sin(x). The particular solution, yp, can be obtained using the method of undetermined coefficients for the nonhomogeneous part, -10x+e^(-x). The final solution y is the sum of yh and yp.

Explanation:

The nonhomogeneous differential equation you have provided is in the form of y″+4y′+5y=-10x+e^(-x).

To find the particular solution (yp), we first need to find the homogeneous solution. The characteristic equation of the associated homogeneous differential equation is r^2+4r+5=0. Solving this quadratic equation, we obtain complex roots as r = -2±i. Hence, the homogeneous solution (yh) is expressed as yh= c1e^-2x cos(x) + c2e^-2x sin(x)

Next, to find yp for f(x)= -10x+e^(-x), we use the method of undetermined coefficients. However, due to the limitation of the platform, it would be too complicated to carry out this procedure here.

Eventually, the final solution of the original nonhomogeneous differential equation will be obtained by adding yh and yp, i.e., y= yh+yp.

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Evaluate ∫∫S z dS, where S is the surface whose sides S1 are given by the cylinder x2 + y2 = 81, whose bottom S2 is the disk x2 + y2 ≤ 81 in the plane z = 0, and whose top S3 is the part of the plane z = 9 + x that lies above S2.

Answers

The integral of [tex]z[/tex] over [tex]S[/tex] is equal to the sum of the integrals of [tex]z[/tex] over [tex]S_1,S_2,S_3[/tex].

[tex]S_1[/tex]:

Parameterize the surface by

[tex]\vec r(u,v)=(9\cos u,9\sin u,v)[/tex]

with [tex]0\le u\le2\pi[/tex] and [tex]0\le v\le9+9\cos u[/tex]. Take the normal vector to [tex]S_1[/tex] to be

[tex]\dfrac{\partial\vec r}{\partial u}\times\dfrac{\partial\vec r}{\partial v}=(9\cos u,9\sin u,0)[/tex]

Then the integral of [tex]z[/tex] over [tex]S_1[/tex] is

[tex]\displaystyle\iint_{S_1}z\,\mathrm dS=\int_0^{2\pi}\int_0^{9+9\cos u}v\|(9\cos u,9\sin u,0)\|\,\mathrm du\,\mathrm dv=\frac{2187\pi}2[/tex]

[tex]S_2[/tex]:

Parameterize [tex]S_2[/tex] by

[tex]\vec s(u,v)=(u\cos v,u\sin v,0)[/tex]

with [tex]0\le u\le9[/tex] and [tex]0\le v\le2\pi[/tex]. Since [tex]z=0[/tex], the integral over [tex]S_2[/tex] is also 0.

[tex]S_3[/tex]:

Parameterize [tex]S_3[/tex] by

[tex]\vec t(u,v)=(u\cos v,u\sin v,9+u\cos v)[/tex]

with [tex]0\le u\le9[/tex] and [tex]0\le v\le2\pi[/tex]. The normal to [tex]S_3[/tex] is

[tex]\dfrac{\partial\vec t}{\partial u}\times\dfrac{\partial\vec t}{\partial v}=(-u,0,u)[/tex]

so that the integral over [tex]S_3[/tex] is

[tex]\displaystyle\iint_{S_3}z\,\mathrm dS=\int_0^{2\pi}\int_0^9(9+u\cos v)\|(-u,0,u)\|\,\mathrm du\,\mathrm dv=729\sqrt2\,\pi[/tex]

Putting the results together, the integral of [tex]z[/tex] over [tex]S[/tex] is

[tex]\iint_Sz\,\mathrm dS=\boxed{\left(\frac{2187}2+729\sqrt2\right)\pi}[/tex]

Final answer:

The procedure to evaluate this integral begins by evaluating integrals over the three distinct parts of the surface: the side, bottom, and top. Both the side and bottom integrals are zero and the integral over the top can be evaluated using polar coordinates, however, without specified boundaries for the upper bound, we cannot determine the exact result.

Explanation:

The task is to evaluate a surface integral over a surface S, which consists of a cylinder, a disk on the bottom, and a plane on the top. The surface integral of a scalar function z over a surface S is computed by taking the antiderivative of the function with respect to both dimensions defining the area. Since S consists of three parts, S1 (the side), S2 (the bottom), and S3 (the top), we must perform this process for each part and sum the results.

The key steps in the procedure are:

Evaluate the integral over S1. Here, the coordinates x and y satisfy the equation x^2 + y^2 = 81, but since z is constant along the side surface of the cylinder, the integral over S1 is zero.Evaluate the integral over S2. Since it lies in the plane z = 0, the integral over the bottom disk S2 is also zero.Evaluate the integral over S3. As z takes the form of z = 9 + x over S3, this integral can be evaluated using polar coordinates and afterward performing an integration, remembering that x = r cos θ in polar coordinates

Summing the results of our calculations on S1, S2, and S3 would yield the final answer. Unfortunately, without the boundaries for the upper bound for the integration, we cannot provide the exact result.

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5. The superintendent of the local school district claims that the children in her district are brighter, on average, than the general population. To determine the aptitude of her district's children, a study was conducted. The results of her district's test scores were: 105, 109, 115, 112, 124, 115, 103, 110, 125, 99. If the mean of the general population of school children is 106, what could be said about her claim? Use alpha = .05

Answers

Answer:

We conclude that children in district are brighter, on average, than the general population.

Step-by-step explanation:

We are given the following data set:

105, 109, 115, 112, 124, 115, 103, 110, 125, 99

Formula:

[tex]\text{Standard Deviation} = \sqrt{\displaystyle\frac{\sum (x_i -\bar{x})^2}{n-1}}[/tex]  

where [tex]x_i[/tex] are data points, [tex]\bar{x}[/tex] is the mean and n is the number of observations.  

[tex]Mean = \displaystyle\frac{\text{Sum of all observations}}{\text{Total number of observation}}[/tex]

[tex]Mean =\displaystyle\frac{1117}{10} = 111.7[/tex]

Sum of squares of differences = 642.1

[tex]S.D = \sqrt{\frac{642.1}{49}} = 8.44[/tex]

We are given the following in the question:  

Population mean, μ = 106

Sample mean, [tex]\bar{x}[/tex] = 111.7

Sample size, n = 10

Alpha, α = 0.05

Sample standard deviation, s = 8.44

First, we design the null and the alternate hypothesis

[tex]H_{0}: \mu = 106\\H_A: \mu > 106[/tex]

We use one-tailed(right) t test to perform this hypothesis.

Formula:

[tex]t_{stat} = \displaystyle\frac{\bar{x} - \mu}{\frac{s}{\sqrt{n}} }[/tex]

Putting all the values, we have

[tex]t_{stat} = \displaystyle\frac{111.7 - 106}{\frac{8.44}{\sqrt{10}} } = 2.135[/tex]

Now,

[tex]t_{critical} \text{ at 0.05 level of significance, 9 degree of freedom } = 1.833[/tex]

Since,                  

[tex]t_{stat} > t_{critical}[/tex]

We fail to accept the null hypothesis and reject it. We accept the alternate hypothesis.

We conclude that children in district are brighter, on average, than the general population.

The following information regarding a portfolio of two stocks are given: w1 = .25, w2 = .75, E(R1) = .08, and E(R2) = .15.

Which of the following regarding the portfolio expected return, E(Rp), is correct?
-.3640
-.2300
-.1325
-.1699

Answers

Answer:

0.1325

Step-by-step explanation:

Weight of the first stock (w1) = .25

Weight of the second stock (w2) = .75

Expected return for the first stock (E(R1)) = .08

Expected return for the second stock (E(R2)) = .15

The expected return of the portfolio is given by the weighted average of the expected return of each stock:

[tex]E(R_p)=w_1*E(R_1)+w_2*E(R_2)\\E(R_p)=0.25*.08 +0.75*.15\\E(R_p)=0.1325[/tex]

The portfolio expected return, E(Rp), is 0.1325

A researcher wants to find a 90% confidence interval for the population proportion of those who support additional handgun control. She collects an SRS of 80 people, 50 of whom say they support additional controls. Which of these is the correct confidence interval?a. (.52, .73)b. (.54, .71)c. (.49, .76)d. (.51, .75)e. (.58, .68)

Answers

Answer: b. (.54, .71)

Step-by-step explanation:

Confidence interval for population proportion is given by :-

[tex]\hat{p}\pm z\sqrt{\dfrac{\hat{p}(1-\hat{p})}{n}}[/tex]

,where [tex]\hat{p}[/tex] = sample proportion

z= Critical z-value

n= sample size.

Let p be the proportion of people who support additional handgun control.

As per given , we have

n= 80

[tex]\hat{p}=\dfrac{50}{80}=0.625[/tex]

Critical z-value for 90% confidence interval is 1.645

Now , a 90% confidence interval for the population proportion of those who support additional handgun control will become:

[tex]0.625\pm (1.645)\sqrt{\dfrac{0.625(1-0.625)}{80}}[/tex]

[tex]=0.625\pm (1.645)\sqrt{0.0029296875}[/tex]

[tex]=0.625\pm 0.089\\\\=(0.625-0.089, 0.625+0.089)\\\\=(0.536,\ 0.714)\approx(0.54,\ 0.71)[/tex]

So the correct answer is : b. (.54, .71)

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