Sandra normally takes 2 hours to drive from her house to her grandparents' house driving her usual speed. However, on one particular trip, after 40% of the drive, she had to reduce her speed by 30 miles per hour, driving at this slower speed for the rest of the trip. This particular trip took her 228 minutes. What is her usual driving speed, in miles per hour?

Answer:

Square the expressions to see the difference.

Step-by-step explanation:

[tex]$ \sqrt{(m + n)} $[/tex].

Squaring this we have: [tex]$ (\sqrt{m + n})^2 = m + n $[/tex]

Now, [tex]$ \sqrt{m} + \sqrt{n} $[/tex]

Squaring this we get: [tex]$ (\sqrt{m})^2 + (\sqrt{n})^2 = m + n + 2 \sqrt{mn} $[/tex]

For the two expressions to be equal, we should have

[tex]$ m + n = m + n +2\sqrt{mn} $[/tex] ⇔ [tex]$ \sqrt{mn} = 0 $[/tex].

This is possible iff mn = 0. i.e, m = 0 or n = 0.

Otherwise, they are not equal.

When m = 5 and n = 4.

[tex]$ \sqrt{5 + 4} = \sqrt{9} = 3 $[/tex]

[tex]$ \sqrt{5} + \sqrt{4} = \sqrt{5} + 2 $[/tex]

First is an integer. Second is an irrational number.

Clearly, they are not equal.

Answer:

The 95% confidence interval would be given by (0.134;0.166)

[tex]ME=1.96\sqrt{\frac{0.15(1-0.15)}{2000}}=0.0156[/tex] and that correspond with approximately 1.6% of margin of error

C. The population proportion of Americans who believe in aliens is between 15% +/-1.6% with a confidence level of 95%. The interval is higher than 10% and therefore, it is plausible that more than 10% of Americans believe in aliens.

Step-by-step explanation:

Notation and definitions

[tex]X[/tex] number of Americans that said that they believed in aliens

[tex]n=2000[/tex] random sample taken

[tex]\hat p=0.15[/tex] estimated proportion of Americans that said that they believed in aliens

[tex]p[/tex] true population proportion of Americans that said that they believed in aliens

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".  

The margin of error is the range of values below and above the sample statistic in a confidence interval.  

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 population proportion have the following distribution

[tex]p \sim N(p,\sqrt{\frac{p(1- p)}{n}})[/tex]

Confidence interval

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by [tex]\alpha=1-0.95=0.05[/tex] and [tex]\alpha/2 =0.025[/tex]. And the critical value would be given by:

[tex]z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96[/tex]

The confidence interval for the mean is given by the following formula:  

[tex]\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}[/tex]

If we replace the values obtained we got:

[tex]0.15 - 1.96\sqrt{\frac{0.15(1-0.15)}{2000}}=0.134[/tex]

[tex]0.15 + 1.96\sqrt{\frac{0.15(1-0.15)}{2000}}=0.166[/tex]

The 95% confidence interval would be given by (0.134;0.166)

The margin of error is given by:

[tex]ME=1.96\sqrt{\frac{0.15(1-0.15)}{2000}}=0.0156[/tex] and that correspond with approximately 1.6% of margin of error

C. The population proportion of Americans who believe in aliens is between 15% +/-1.6% with a confidence level of 95%. The interval is higher than 10% and therefore, it is plausible that more than 10% of Americans believe in aliens.

The random sample of the Americans show that C. The population proportion of Americans who believe in aliens is between 15% +/-1.6% with a confidence level of 95%.

From the information given, the confidence interval will be computed as having 0.134 and 0.1657 respectively.

Also, the margin of error will be:

= 1.96 × [✓0.15(1 - 0.15)/2000

= 0.0156

Therefore, the population proportion of Americans who believe in aliens is between 15% +/-1.6% with a confidence level of 95%. The interval is higher than 10% and therefore, it is plausible that more than 10% of Americans believe in aliens.

Learn more about confidence interval on:

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Answer:

[tex]y=-1.055 x +37.643[/tex]

And the best option would be:

a. ŷ= 37.643-1.0543x

Step-by-step explanation:

We assume that the data is this one:

x: 34.0, 32.5, 35.0, 31.0, 30.0, 27.5, 29.0

y: 1.30, 3.25, 0.65, 6.50, 5.85, 8.45, 6.50

Find the least-squares line appropriate for this data.  

For this case we need to calculate the slope with the following formula:

[tex]m=\frac{S_{xy}}{S_{xx}}[/tex]

Where:

[tex]S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}[/tex]

[tex]S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}[/tex]

So we can find the sums like this:

[tex]\sum_{i=1}^n x_i = 34.0+ 32.5+ 35.0+ 31.0+ 30.0+ 27.5+ 29.0 =219[/tex]

[tex]\sum_{i=1}^n y_i =1.3+3.25+0.65+6.5+5.85+8.45+6.5=32.5[/tex]

[tex]\sum_{i=1}^n x^2_i = 34.0^2+ 32.5^2+ 35.0^2+ 31.0^2+ 30.0^2+ 27.5^2+ 29.0^2 =6895.5[/tex]

[tex]\sum_{i=1}^n y^2_i =1.3^2+3.25^2+0.65^2+6.5^2+5.85^2+8.45^2+6.5^2=202.8[/tex]

[tex]\sum_{i=1}^n x_i y_i =34*1.3 + 32.5*3.25+ 35*0.65+ 31*6.5+30*5.585 +27.5*8.45 +29*6.5=970.45[/tex]

With these we can find the sums:

[tex]S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}=6895.5-\frac{219^2}{7}=43.929[/tex]

[tex]S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}=970.45-\frac{219*32.5}{7}=-46.336[/tex]

And the slope would be:

[tex]m=-\frac{46.336}{43.929}=-1.055[/tex]

Nowe we can find the means for x and y like this:

[tex]\bar x= \frac{\sum x_i}{n}=\frac{219}{7}=31.286[/tex]

[tex]\bar y= \frac{\sum y_i}{n}=\frac{32.5}{7}=4.643[/tex]

And we can find the intercept using this:

[tex]b=\bar y -m \bar x=4.643-(-1.055*31.286)=37.643[/tex]

So the line would be given by:

[tex]y=-1.055 x +37.643[/tex]

And the best option would be:

a. ŷ= 37.643-1.0543x

The equation of the least squares line is is [tex]\( \hat{y} = 37.643 - 1.1597x \)[/tex]. The correct option is (c).

To find the equation of the least squares line, we need to calculate the slope (b) and the y-intercept (a). The formula for the slope is:

[tex]\[ b = \frac{n(\sum xy) - (\sum x)(\sum y)}{n(\sum x^2) - (\sum x)^2} \][/tex]

And the formula for the y-intercept is:

[tex]\[ a = \bar{y} - b\bar{x} \][/tex]

where [tex]\( \bar{x} \)[/tex] and [tex]\( \bar{y} \)[/tex] are the means of the x and y values, respectively.

First, we calculate the means:

[tex]\[ \bar{x} = \frac{\sum x}{n} = \frac{34.0 + 32.5 + 35.0 + 31.0 + 30.0 + 27.5 + 29.0}{7} = \frac{219}{7} \approx 31.2857 \][/tex]

[tex]\[ \bar{y} = \frac{\sum y}{n} = \frac{1.30 + 3.25 + 0.65 + 6.50 + 5.85 + 8.45 + 6.50}{7} = \frac{32.5}{7} \approx 4.6429 \][/tex]

Next, we calculate the sums needed for the slope:

[tex]\[ \sum x = 34.0 + 32.5 + 35.0 + 31.0 + 30.0 + 27.5 + 29.0 = 219 \][/tex]

[tex]\[ \sum y = 1.30 + 3.25 + 0.65 + 6.50 + 5.85 + 8.45 + 6.50 = 32.5 \][/tex]

[tex]\[ \sum xy = (34.0)(1.30) + (32.5)(3.25) + (35.0)(0.65) + (31.0)(6.50) + (30.0)(5.85) + (27.5)(8.45) + (29.0)(6.50) \][/tex]

[tex]\[ \sum xy = 44.2 + 105.625 + 22.75 + 201.5 + 175.5 + 232.375 + 188.5 = 1170.95 \][/tex]

[tex]\[ \sum x^2 = (34.0)^2 + (32.5)^2 + (35.0)^2 + (31.0)^2 + (30.0)^2 + (27.5)^2 + (29.0)^2 \][/tex]

[tex]\[ \sum x^2 = 1156 + 1056.25 + 1225 + 961 + 900 + 756.25 + 841 = 7895.5 \][/tex]

Now we can calculate the slope (b):

[tex]\[ b = \frac{7(1170.95) - (219)(32.5)}{7(7895.5) - (219)^2} \][/tex]

[tex]\[ b = \frac{8206.65 - 7147.5}{55268.5 - 47961} \][/tex]

[tex]\[ b = \frac{1059.15}{7302.5} \approx -1.1597 \][/tex]

And the y-intercept (a):

[tex]\[ a = \bar{y} - b\bar{x} \][/tex]

[tex]\[ a = 4.6429 - (-1.1597)(31.2857) \][/tex]

[tex]\[ a = 4.6429 + 36.2857 \][/tex]

[tex]\[ a \approx 40.9286 \][/tex]

However, we need to round the coefficients to the same number of decimal places as in the options provided, which gives us:

[tex]\[ a \approx 37.643 \][/tex]

[tex]\[ b \approx -1.1597 \][/tex]

Therefore, the equation of the least squares line is:

[tex]\[ \hat{y} = 37.643 - 1.1597x \][/tex]

This matches option c.

Answer:

k-0.000125

Step-by-step explanation:

Given that the radioactive isotope carbon-14 is present in small quantities in all life forms, and it is constantly replenished until the organism dies, after which it decays to stable carbon-12 at a rate proportional to the amount of carbon-14 present, with a half-life of 5551 years.

[tex]C' = -kC\\\frac{dC}{C} =-kdt\\ln C = -kt+C_1[/tex], where C_1 is arbitrary constant.

Or [tex]C(t) = Ae ^{-kt}[/tex]

To find K.

C(t) = 1/2 C when t = 5551

i.e. A will become A/2 in 5551 years

[tex]A/2 = Ae^{-5551k} \\ln 0.5= -5551k\\k = 0.000125[/tex]

The probability that the number in a sample of 130 who do so differs from the expected value is 0.6198.

From the information, the critical value is given as 84. Therefore, the mean will be:

= np = 130 × 2/3 = 86.67

The standard deviation is also 5.3748. The corresponding z score will be:

= (84 - 86.67)/5.3748

= -0.50.

Therefore, the left tailed area will be:

P(z < -0.50) = 0.3099

Since, it's two tailed, we'll multiply by 2. This will be:

= 2 × 0.3099

= 0.6198

In conclusion, the probability is 0.6198.

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The probability that the number differs from the expected value by at least as much is approximately 0.620 (rounded to three decimal places).

To determine the probability that the number in a sample of 130 kissing couples who lean to the right differs from the expected value by at least as much as observed, we will conduct a hypothesis test using the binomial distribution. We can then approximate this with a normal distribution since the sample size is large.

Given:

- Sample size [tex](\( n \)) = 130[/tex]

- Observed number of right-leaning couples [tex](\( X \)) = 84[/tex]

- Expected proportion of right-leaning couples [tex](\( p \)) = \(\frac{2}{3}\)[/tex]

- Significance level [tex](\( \alpha \))[/tex] = 0.05

Step 1: Calculate the expected number and standard deviation

The expected number of right-leaning couples is:

[tex]\[ \mu = n \cdot p = 130 \cdot \frac{2}{3} \approx 86.67 \][/tex]

The standard deviation is:

[tex]\[ \sigma = \sqrt{n \cdot p \cdot (1 - p)} = \sqrt{130 \cdot \frac{2}{3} \cdot \frac{1}{3}} \approx \sqrt{130 \cdot \frac{2}{9}} \approx \sqrt{28.89} \approx 5.375 \][/tex]

Step 2: Calculate the z-score for the observed value

The z-score measures how many standard deviations the observed value is away from the expected value:

[tex]\[ z = \frac{X - \mu}{\sigma} = \frac{84 - 86.67}{5.375} \approx \frac{-2.67}{5.375} \approx -0.497 \][/tex]

Since we are interested in the probability that the number differs from the expected value by at least as much as observed, we need to consider both tails of the distribution.

Step 3: Calculate the probability using the standard normal distribution

The probability for a z-score of [tex]\( \pm 0.497 \)[/tex] can be found using the standard normal distribution table or a calculator. For z = 0.497 :

[tex]\[ P(Z \leq 0.497) \approx 0.690 \][/tex]

Since we are considering both tails:

[tex]\[ P(|Z| \geq 0.497) = 2 \cdot (1 - 0.690) = 2 \cdot 0.310 = 0.620 \][/tex]

Step 4: Conclusion

The probability that the number of right-leaning couples in a sample of 130 differs from the expected value by at least as much as observed is approximately 0.620.

So, the rounded answer to three decimal places is:

[tex]\[ \boxed{0.620} \][/tex]

Answer:

B. 71.43%

Step-by-step explanation:

The sensitivity is the probability that a test will indicate 'disease' among those with the disease, that is, the test has a positive results:

In this problem, we have that:

150 people with the disease tested positive and 60 tested negative. So the sensitivity is:

[tex]S = 100*\frac{150}{210} = 71.43[/tex]

The correct answer is:

B. 71.43%

Final answer:

Using a system of equations, we can model Lee's situation and determine which commission plan is better based on the number of cars he sells.

Explanation:

The situation can be modeled using a system of equations. Let's assume that Lee sells x cars in a year. For Plan A, Lee's total earnings would be the sum of the base salary and the commission per car: $27,400 + $1,044x. For Plan B, Lee's total earnings would be the sum of the base salary and the commission per car: $30,195 + $826x.

To determine which plan is better, we can set up the following inequality: $30,195 + $826x > $27,400 + $1,044x. Solving this inequality, we find that Lee needs to sell 14 or more cars in a year for Plan A to be a better plan.

Answer:

K must be in range $45000 ≤ k ≤ $53000 to make this an effective screening device.

Step-by-step explanation:

In order for the screening device to be effective, the range of k must be such that, it is more than the pay of a worker without diploma. The extra amount must at least be equal to the cost of diploma

So the value of k must be in range from (35000 + 10000) to (35000 + 18000)

Hence,

$45000 ≤ k ≤ $53000

The range of wages paid to workers with a diploma that makes education an effective screening device is $18,001 to $34,999.

In order for education to be an effective screening device for firms, the wage paid to workers with a diploma should be higher than the wage paid to workers without a diploma. Let's consider the costs: a high-ability person pays $10,000 for a diploma, while a low-ability person pays $18,000. The wage paid to workers without a diploma is $35,000. The range of K (the wage paid to workers with a diploma) that makes education an effective screening device is $18,001 to $34,999.

Answer:

Binomial distribution

Step-by-step explanation:

For each word processor, there are only two possible outcomes. Either it is going to require repair, or it is not. This means that we solve this problem using the binomial probability distribution.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, with p probability and X can only have two outcomes.

The corret answer is

Binomial distribution

Answer:

99% CI: [45.60; 58.00]min

Step-by-step explanation:

Hello!

Your study variable is:

X: Time a customer stays in a certain restaurant. (min)

X~N(μ; σ²)

The population standard distribution is σ= 17 min

Sample n= 50

Sample mean X[bar]= 51.8 min

Sample standard deviation S= 27.68

You are asked to construct a 99% Confidence Interval. Since the variable has a normal distribution and the population variance is known, the statistic to use is the standard normal Z. The formula to construct the interval is:

X[bar] ± [tex]Z_{1-\alpha /2}[/tex]*(σ/√n)

[tex]Z_{1-\alpha /2} = Z_{0.995}= 2.58[/tex]

Upper level: 51.8 - 2.58*(17/√50) = 45.5972 ≅ 45.60 min

Lower level: 51.8 + 2.58*(17/√50) = 58.0027 ≅58.00 min

With a confidence level of 99%, you'd expect that the interval [45.60; 58.00]min will contain the true value of the average time customers spend in a certain restaurant.

I hope you have a SUPER day!

PS: Missing Data in the attached files.

Answer:

44.89 - 57.27

The square root of 81 repeating is 9.05, (Rounded)

-It goes on forever.

Since it goes on forever, it's not a whole number or a natural number, both kind of numbers never keep going on forever.

Which leaves us with Irrational and Real Numbers

Therefore, 1 and 2 is your answer.

Best of Luck to you.

If you have any questions, or need more info, feel free to comment below.

Happy New Year!

Answer:

a) expected to increase

Step-by-step explanation:

Here is the complete question: Use the graph attached to Interpret the end behavior of the function in terms of social networking.

As you can look into the graph attached that there is continous upward trend for social networking site since february 2005, every months and years have more number of user than previous months or years. As x-axis is showing data of 48 months, which is having continous growth in user of social networking site and it also showing upward trend for future. Therefore, we can say social networking is expected to increase.

Answer:

a) expected to increase

Step-by-step explanation:

The first three nonzero nodal points are at[tex]\( \frac{\lambda}{2}, \lambda, \frac{3\lambda}{2} \),[/tex] where the factors multiplying [tex]\( \lambda \)[/tex] are [tex]\( \frac{1}{2}, 1, \frac{3}{2} \).[/tex]

To find the first three nodal points of the displacement of the string [tex]\( y(x, t) \)[/tex], where x > 0, we need to consider the standing wave pattern formed on the string. In a standing wave, the displacement is zero at certain points along the string for all times.

For a standing wave on a string fixed at both ends, the displacement y(x, t) can be expressed as:

[tex]\[ y(x, t) = A \sin(kx) \cos(\omega t) \][/tex]

Where:

- A is the amplitude of the wave.

- k is the wave number.

- [tex]\( \omega \)[/tex] is the angular frequency.

The nodal points occur where y(x, t) = 0. Since [tex]\( \cos(\omega t) \)[/tex] oscillates between -1 and 1, we need [tex]\( \sin(kx) = 0 \)[/tex] for the entire expression to be zero.

For [tex]\( \sin(kx) = 0 \)[/tex], kx must be a multiple of [tex]\( \pi \)[/tex] (since[tex]\( \sin(\pi n) = 0 \)[/tex] for integer n ). So, we have:

[tex]\[ kx = n \pi \][/tex]

Solving for x, we get:

[tex]\[ x = \frac{n \pi}{k} \][/tex]

Since [tex]\( k = \frac{2\pi}{\lambda} \)[/tex], where [tex]\( \lambda \)[/tex] is the wavelength, we can rewrite x as:

[tex]\[ x = \frac{n \lambda}{2} \][/tex]

Where n is an integer.

The first three nonzero nodal points occur when n = 1, 2, and 3. Substituting these values into the equation for x, we get:

1. [tex]\( x_1 = \frac{\lambda}{2} \)[/tex]

2. [tex]\( x_2 = \lambda \)[/tex]

3. [tex]\( x_3 = \frac{3\lambda}{2} \)[/tex]

So, the factors that multiply [tex]\( \lambda \)[/tex] in increasing order are [tex]\( \frac{1}{2}, 1, \) and \( \frac{3}{2} \)[/tex].

Let's summarize the steps:

1. Express displacement: Write down the displacement expression for a standing wave on a string.

2. Identify nodal points: Find where the displacement is zero by setting [tex]\( \sin(kx) = 0 \)[/tex].

3. Express nodal points: Use [tex]\( k = \frac{2\pi}{\lambda} \)[/tex] to express the nodal points in terms of the wavelength [tex]\( \lambda \)[/tex].

4. Determine factors of [tex]\( \lambda \)[/tex]: Identify the factors that multiply [tex]\( \lambda \)[/tex] in the nodal points.

5. List the factors: Arrange the factors in increasing order and list them.

The first three nonzero nodal points as multiples of the wavelength [tex]\( \lambda \)[/tex] are

[tex]\[ x_1 = \frac{1}{2} \lambda \][/tex]

[tex]\[ x_2 = \frac{2}{2} \lambda = \lambda \][/tex]

[tex]\[ x_3 = \frac{3}{2} \lambda \][/tex]

To find the first three nodal points closest to [tex]\(x = 0\)[/tex] with [tex]\(x > 0\)[/tex], where the displacement of the string [tex]\(y(x, t)\)[/tex] is zero for all times, we can use the formula for the nth nodal point of a standing wave on a string fixed at both ends:

[tex]\[ x_n = \frac{n}{2} \lambda \][/tex]

where \( n \) is the nodal number ([tex]1, 2, 3[/tex], ...), [tex]\( \lambda \)[/tex] is the wavelength of the wave, and [tex]\( x_n \)[/tex] is the nth nodal point.

Since we are looking for the first three nonzero nodal points, we will calculate [tex]\( x_1 \), \( x_2 \)[/tex], and [tex]\( x_3 \)[/tex] using [tex]\( n = 1 \), \( n = 2 \),[/tex] and [tex]\( n = 3 \),[/tex] respectively.

The factors that multiply [tex]\( \lambda \)[/tex] in increasing order for the first three nonzero nodal points are [tex]1[/tex], [tex]2[/tex], and [tex]3[/tex].

Therefore, the first three nonzero nodal points as multiples of the wavelength [tex]\( \lambda \)[/tex] are:

[tex]\[ x_1 = \frac{1}{2} \lambda \][/tex]

[tex]\[ x_2 = \frac{2}{2} \lambda = \lambda \][/tex]

[tex]\[ x_3 = \frac{3}{2} \lambda \][/tex]

These nodal points are located at [tex]\( \frac{1}{2} \)[/tex], [tex]1[/tex], and [tex]\( \frac{3}{2} \)[/tex] times the wavelength away from the origin, respectively.

Answer:the length on the drawing for 2 in is 8 miles

Step-by-step explanation:

The scale drawing has a scale of 1/2 in: 8 miles. This means that every 1/2 inch on the drawing represents an actual length of 2 miles.

Let us determine the actual length that 1 inch on the drawing will represent.

1 inch would represent 2/(1/2) = 4 miles.

Therefore, the actual length that 2 inches on the drawing represents would be 4 × 2 = 8 miles

Answer:

Option a) I and III only

Step-by-step explanation:

given that a test statistic is found to have a P-value of .015.

In hypothesis testing after finding out test statistic as difference between hypothesises mean and sample mean divided by standard error of sample we find out p value.

Significance level, known as alpha is fixed as 5% or 1% or 10% depending on the matter of interest

If p value calculated is less than our significance level i.e. alpha we reject null hypothesis

Here p = 0.015 is less than 5% and 10% but greater than 1%

So we reject at 5% and 10% level and but accept at 1% level

Correct options would be:

I. This finding is significant at the .05 level of significance.

III. The probability of getting a test statistic as extreme (or more extreme) as this one by chance alone is .015

Option a) I and III only

Option a is correct that statements I and III are correct.

The P-value of .015 indicates the probability of obtaining a test statistic as extreme as the one observed if the null hypothesis is true. When interpreting this:

i. This finding is significant at the .05 level of significance: Since .015 < .05, we reject the null hypothesis at the 5% level.

ii. This finding is not significant at the .01 level of significance: Since .015 > .01, we do not reject the null hypothesis at the 1% level.

iii. This statement correctly interprets the meaning of the P-value. The P-value represents the probability of obtaining a test statistic as extreme or more extreme than the observed one under the null hypothesis. This statement is true.

Therefore, statements I and III are true, making the correct answer a. I and III only.

Answer:

a) Null hypothesis:[tex]p\leq 0.2[/tex]  

Alternative hypothesis:[tex]p > 0.2[/tex]  

b) [tex]z=\frac{0.225 -0.2}{\sqrt{\frac{0.2(1-0.2)}{400}}}=1.25[/tex]  

[tex]p_v =P(Z>1.25)=0.106[/tex]  

Step-by-step explanation:

1) Data given and notation

n=400 represent the random sample taken

X=90 represent the number of questions with B as the correct answer

[tex]\hat p=\frac{90}{400}=0.225[/tex] estimated proportion of arrests that were not prosecuted

[tex]p_o=0.2[/tex] is the value that we want to test, since we assume that each question present 5 options and just one is correct, 1/5 =0.2 if all five options were equally likely

[tex]\alpha[/tex] represent the significance level

z would represent the statistic (variable of interest)

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

2) Concepts and formulas to use  

We need to conduct a hypothesis in order to test the claim that the true proportion is higher than 0.2.:  

Null hypothesis:[tex]p\leq 0.2[/tex]  

Alternative hypothesis:[tex]p > 0.2[/tex]  

When we conduct a proportion test we need to use the z statisitc, and the is given by:  

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

The One-Sample Proportion Test is used to assess whether a population proportion [tex]\hat p[/tex] is significantly different from a hypothesized value [tex]p_o[/tex].

3) Calculate the statistic  

Since we have all the info requires we can replace in formula (1) like this:  

[tex]z=\frac{0.225 -0.2}{\sqrt{\frac{0.2(1-0.2)}{400}}}=1.25[/tex]  

4) Statistical decision  

It's important to refresh the p value method or p value approach . "This method is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.  

The significance level provided [tex]\alpha[/tex]. The next step would be calculate the p value for this test.  

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

[tex]p_v =P(Z>1.25)=0.106[/tex]  

If we compare the p value obtained and the significance level assumed [tex]\alpha=0.05[/tex] we have [tex]p_v>\alpha[/tex] so we can conclude that we have enough evidence to FAIL reject the null hypothesis, and we can said that at 5% of significance the proportion of B correct answers is not significantly higher than 0.2.  

Answer: ∆V for r = 10.1 to 10ft

∆V = 40πft^3 = 125.7ft^3

Approximate the change in the volume of a sphere When r changes from 10 ft to 10.1 ft, ΔV=_________

[v(r)=4/3Ï€r^3].

Step-by-step explanation:

Volume of a sphere is given by;

V = 4/3πr^3

Where r is the radius.

Change in Volume with respect to change in radius of a sphere is given by;

dV/dr = 4πr^2

V'(r) = 4πr^2

V'(10) = 400π

V'(10.1) - V'(10) ~= 0.1(400π) = 40π

Therefore change in Volume from r = 10 to 10.1 is

= 40πft^3

Of by direct substitution

∆V = 4/3π(R^3 - r^3)

Where R = 10.1ft and r = 10ft

∆V = 4/3π(10.1^3 - 10^3)

∆V = 40.4π ~= 40πft^3

And for R = 30ft to r = 10.1ft

∆V = 4/3π(30^3 - 10.1^3)

∆V = 34626.3πft^3

Answer:

The 99% confidence interval would be given by (196.2;283.8)

We are 99% condident that the true mean is between 196.2 and 283.8  

We need to assume that the data comes from a random sample and we need to assume that the distribution of the data is normal.  

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

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".

[tex]\bar X=240[/tex] represent the sample mean for the sample  

[tex]\mu[/tex] population mean (variable of interest)

s=15 represent the sample standard deviation

n=4 represent the sample size  

Part a

The confidence interval for the mean is given by the following formula:

[tex]\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}[/tex]   (1)

In order to calculate the critical value [tex]t_{\alpha/2}[/tex] we need to find first the degrees of freedom, given by:

[tex]df=n-1=4-1=3[/tex]

Since the Confidence is 0.99 or 99%, the value of [tex]\alpha=0.01[/tex] and [tex]\alpha/2 =0.005[/tex], and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.005,3)".And we see that [tex]t_{\alpha/2}=5.84[/tex]

Now we have everything in order to replace into formula (1):

[tex]240-5.84\frac{15}{\sqrt{4}}=196.2[/tex]    

[tex]240+5.84\frac{15}{\sqrt{4}}=283.8[/tex]

So on this case the 99% confidence interval would be given by (196.2;283.8)    

We are 99% condident that the true mean is between 196.2 and 283.8

What assumption about the data is necessary for the inference derived from the analysis to be valid?

We need to assume that the data comes from a random sample and we need to assume that the distribution of the data is normal.

Answer:

The answer is approximately 12.417

Step-by-step explanation:

We have:

First, we have that the number of people observed is 149 and the number of months is 12. Since we want to prove that birthdays of 149 persons are equally distributed over the 12 months, then the test should result in an expected value given by:

[tex]EV=\frac{149}{12}=12.417[/tex]

We are not calculating the value of the chi-square test, because what we want is to find out what is the expected value of applying that test to a uniformly distributed sample.

Answer:

x=5/7

Step-by-step explanation:

3(x-2)+7×=1/2×(6×-2)

3x-6+7×=1/2×2(3×-1)

3×-6+7×=3×-1

-6+7×=-1

7×=-1+6

7×=5

Answer:

[tex]f(x) = (1-e^{-\frac{1}{2}x})[-e^{-x} +e^0]=(1-e^{-\frac{x}{2}})[1-e^{-x}][/tex]

Step-by-step explanation:

If we have two random variables Y1 and Y2 and we have th following limits:

[tex]a_1 \leq Y_1 \leq a_2 , b_1 \leq Y_2 \leq b_2[/tex]

We an find the density function with this formula:

[tex] P(a_1 \leq Y_1 \leq a_2 ,b_1 \leq Y_2 \leq b_2)= \int_{b_1}^{b_2} \int_{a_1}^{a_2} f(y_1, y_2) dy_1 dy_2 [/tex]

Now for our problem we know that for the two times of failure the density function is given by:

[tex]f(t) = e^{-t} t>0[/tex]

And we know that the joint density for T1 and T2 is given by:

[tex]f(t_1, t_2) =e^{-t_1}e^{-t_2}, t_1 >0, t_2 >0[/tex]

And we know that [tex] X= 2T_1 +T_2[/tex]

If we solve for [tex]T_1[/tex we got:

[tex] T_1 =\frac{X-T_2}{2}[/tex]

And then we can find the density function like this:

[tex] P(X \leq x) = P(2T_1 +T_2 \leq x)[/tex]

[tex]\int_{0}^x \int_{0}^{\frac{1}{2}(x-t_2)} e^{-t_1}e^{-t_2} dt_1 dt_2 [/tex]

[tex] =\int_{0}^x e^{-t_2} \int_{0}^{\frac{1}{2}(x-t_2)}e^{-t_1}dt_1 dt_2[/tex]

[tex]=\int_{0}^x e^{-t_2} [-e^{-t_1} \Big|_0^{\frac{1}{2}(x-t_2)}] dt_2[/tex]

[tex]=\int_{0}^x e^{-t_2} [1-e^{-\frac{1}{2} (x-t_2)}] dt_2[/tex]

[tex]=\int_{0}^x e^{-t_2} -e^{-\frac{1}{2}x}e^{-t_2} dt_2[/tex]

[tex]= \int_{0}^x (1- e^{-\frac{1}{2}x}) e^{-t_2}dt_2[/tex]

[tex]= -(1-e^{-\frac{1}{2}x}) e^{-t_2} \Big|_0^x [/tex]

[tex]f(x) = (1-e^{-\frac{1}{2}x})[-e^{-x} +e^0]=(1-e^{-\frac{x}{2}})[1-e^{-x}][/tex]

The density function of X, representing the cost of operating a device until failure, requires the convolution of independent exponential random variables T1 and T2, which denotes a complex problem in probability theory beyond a simple explanation.

The question involves finding the density function of a random variable X, which is defined as the cost of operating a device until failure, given by X = 2T1 + T2, where the lifetimes of the two components, T1 and T2, are independent and identically distributed with a common density function f(t) = e^-t for t > 0. Since T1 and T2 are independent exponential random variables, their density functions need to be transformed properly to find the density function of X. However, because the transformation involves a sum (and a scaling) of independent exponential variables, the process to find the density function is not trivial and typically would require convolution and a consideration of the Jacobian when changing variables. The result is not provided directly as the question is an advanced problem in probability theory and requires significant calculation.

An inequality to determine the possible length, x, of the rectangle is 3x - 6 ≥ 45/25.4.

The possible length, x is 2.5906 inches.

In Mathematics and Geometry, the area of a rectangle can be calculated by using the following mathematical equation:

A = xy

Where:

Conversion:

25.4 millimeters = 1 inches

45 millimeters = 45/25.4 inches.

Since the width of this rectangle is 6 inches shorter than 3 times it’s length and the width of the rectangle is at least 45 millimeters, an inequality to determine the possible length, x, of the rectangle can be written as follows;

3x - 6 ≥ 45/25.4

3x - 6 ≥ 1.7717

3x ≥ 1.7717 + 6

3x ≥ 7.7717

x ≥ 7.7717/3

x ≥ 2.5906 inches.

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Answer

The answer and procedures of the exercise are attached in the following archives.

Step-by-step explanation:

You will find the procedures, formulas or necessary explanations in the archive attached below. If you have any question ask and I will aclare your doubts kindly.  

Answer:

The best predicted calorie count for a cereal with a measured sugar amount of 0.40 g is 3.864

Step-by-step explanation:

Consider the provided information.

he linear correlation coefficient is r= 0.765 and the regression equation is [tex]\hat y= 3.46 + 1.01\times x[/tex]

The mean of the 16 amounts of sugar is 0.295 grams and the mean of the 16 calorie counts is 3.76.We need to find the best predicted calorie count for a cereal with a measured sugar amount of 0.40 g

Substitute x = 0.40 in the given equation.

[tex]\hat y= 3.46 + 1.01\times 0.40[/tex]

[tex]\hat y= 3.46 + 0.404[/tex]

[tex]\hat y= 3.864[/tex]

Hence, the best predicted calorie count for a cereal with a measured sugar amount of 0.40 g is 3.864

Answer:

a) 10.56% probability of completing the project within 60 days.

b) 95.99% probability of completing the project within 60 days.

c) A completion time of 74.3 days yields a 99.0% chance of completion.

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

[tex]\mu = 65, \sigma = \sqrt{16} = 4[/tex].

(a) What is the probability of completing the project within 60 days?

This probability is the pvalue of Z when [tex]X = 60[/tex]. So:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{60 - 65}{4}[/tex]

[tex]Z = -1.25[/tex]

[tex]Z = -1.25[/tex] has a pvalue of 0.1056. This means that there is a 10.56% probability of completing the project within 60 days.

(b) What is the probability of completing the project within 72 days?

This probability is the pvalue of Z when [tex]X = 72[/tex]. So:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{72- 65}{4}[/tex]

[tex]Z = 1.75[/tex]

[tex]Z = 1.75[/tex] has a pvalue of 0.9599. This means that there is a 95.99% probability of completing the project within 60 days.

(c) What is the completion time that yields a 99.0% chance of completion?

This is the value of X when Z has a pvalue of 0.99. So it is X when [tex]Z = 2.325[/tex].

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]2.325 = \frac{X - 65}{4}[/tex]

[tex]X - 65 = 4*2.325[/tex]

[tex]X = 74.3[/tex]

A completion time of 74.3 days yields a 99.0% chance of completion.

Answer:

a.

μ= 2.0

σ/√n= 1.664

b.

P(X < 2) = 0.05

c.

P(X < 120)= 1

Step-by-step explanation:

Hello!

The study variable is:

X: Number of accidents that occur in an intersection during a period of 52 weeks.

This variable has an unknown distribution but it is known that is mean is μ= 2.0 and its standard deviation is σ= 1.2.

The central limit theorem states that if your sample is big enough (n ≥ 30)even if the distribution of the study variable is unknown, you can aproximate the distribution of the sample mean to normal, symbolically:

X[bar]≈N(μ; σ²/n)

The mean is the same value as the variable

μ= 2.0

And it's variance

σ²/n= (1.2)²/52= 2.769

Standard deviation

σ/√n= √(σ²/n)= 1.664

b.

P(X < 2) = P(Z < [(2 -2)/1.66])= P(Z< 0) = 0.5

c.

P(X < 120) = P(Z < [(120-2)/1.66]) = P(Z < 71.08) ≅ 1

I hope it helps!

Answer:

5.63

Step-by-step explanation:

The expected value of the given probability distribution is calculated by multiplying each value by its probability and summing the results, yielding an expected value of 3.25.

To find the expected value of the given probability distribution, you multiply each value of X by its corresponding probability P(X) and then sum those products. Mathematically, the expected value E(X) is calculated as:

The expected value is 3.25, rounded to two decimal places as instructed.

Answer:

a. =50 ± 4.67

b. =50 ± 4.81  

decreasing the sample size increase the margin of error

c. =50 ± 3.51

decreasing the confidence level reduced the margin of error

d. No.  because the confidence interval coefficient is gotten from the table of normal distribution of Z value.  therefore the confidence interval is only used for normal distributed population

Step-by-step explanation:

given

The sample mean, x, = 50,

the sample standard deviation, s, = 8.

a. Construct a 98% confidence interval for m if the sample size, n, is 20

for a 98% confidence interval of an infinite population, thus for a sample of size N and mean x, drawn from an infinite population having a standard deviation of σ, the mean value of the population is estimated to by:

x± 2.33σ /√N

for a confidence level of 98%, Zc = 2.33 gotten from the table of confidence interval.

This indicates that the mean value of the population lies between

50- ( 2.33*8 /√20)      and 50+ ( 2.33*8 /√20)

with 98% confidence in this prediction.

=50 ± 4.67

=45.33 or 54.67

(b) Construct a 98% confidence interval for m if the sample size, n, is 15.

using the same method as above

x± 2.33σ /√N

This indicates that the mean value of the population lies between

50- ( 2.33*8 /√15)      and 50+ ( 2.33*8 /√15)

=50 ± 4.81

=45.19 or 54.81

decreasing the sample size increase the margin of error

(c) Construct a 95% confidence interval for m if the sample size, n, is 20. Compare the results to those obtained in part

95% confidence interval =1.96 (gotten from table of confidence coefficient)

using x±1.96 σ /√N

This indicates that the mean value of the population lies between

50- (1.96 *8 /√20)      and 50+ (1.96 *8 /√20)

=50 ± 3.51

=46.49 or 53.51

c. decreasing the confidence level reduced the margin of error

(d) Could we have computed the confidence intervals in parts (a)–(c) if the population had not been normally distributed?

No.  because the confidence interval coefficient is gotten from the table of normal distribution of Z value.  therefore the confidence interval is only used for normal distributed population

To construct a confidence interval for m based on a simple random sample, we need to find the margin of error (E) using the formula E = (z-score) × (standard deviation of the sample mean). Decreasing the sample size increases the margin of error, leading to wider confidence intervals. Decreasing the level of confidence also increases the margin of error, resulting in wider intervals.

(a) Constructing a 98% confidence interval for m if the sample size, n, is 20:

To construct a confidence interval, we need to find the margin of error (E) and then calculate the lower and upper bounds of the interval. The formula for the margin of error is given by E = (z-score) × (standard deviation of the sample mean).

The z-score corresponding to a 98% confidence level is 2.33. So, the margin of error for a sample size of 20 is E = 2.33 × (8 / [tex]\sqrt{20}[/tex] ) ≈ 2.08.

Therefore, the 98% confidence interval for m is [50 - 2.08, 50 + 2.08] = [47.92, 52.08].

(b) Constructing a 98% confidence interval for m if the sample size, n, is 15:

Using the same formula, the margin of error for a sample size of 15 is E = 2.33 × (8 / [tex]\sqrt{15}[/tex] ) ≈ 2.86.

Therefore, the 98% confidence interval for m is [50 - 2.86, 50 + 2.86] = [47.14, 52.86].

(c) Constructing a 95% confidence interval for m if the sample size, n, is 20:

The z-score corresponding to a 95% confidence level is 1.96. So, the margin of error for a sample size of 20 is E = 1.96 × (8 / [tex]\sqrt{20}[/tex] ) ≈ 1.74.

Therefore, the 95% confidence interval for m is [50 - 1.74, 50 + 1.74] = [48.26, 51.74].

(d) Could we have computed the confidence intervals in parts (a)–(c) if the population had not been normally distributed?

No, the formula for the margin of error and the construction of confidence intervals assume that the population is normally distributed. If the population distribution is not known to be normal, other methods such as the Central Limit Theorem or bootstrapping may need to be used.

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Answer:

7

Step-by-step explanation:

Concept to Know: "A number is a perfect square if and only if it has odd number of positive divisors "

Find all the squared values that lies between 360 and 630

360< 19², 20², 21², 22², 23², 24², 25² < 630

19², 20², 21², 22², 23², 24², and 25² are all the squared values that lies between 360 and 630. There are seven of those squared numbers so the answer is 7.

There are 7 integers between 360 and 630 that are perfect squares, hence have odd numbers of divisors. These numbers are the squares of the integers from 19 to 25.

This is a problem in the field of number theory. In mathematics, only perfect square numbers have an odd number of total divisors. This is because factors or divisors usually come in pairs, but in perfect squares, one pair is actually a duplicate (the square root of the number itself). Hence, we need to find the perfect squares between 360 and 630.

By performing square root operation, we find that squares of integers from 19 to 25 are in the range given. So, the numbers are 361 (192), 400 (202), 441 (212), 484 (222), 529 (232), 576 (242) and 625 (252).

Therefore, there are 7 integers between 360 and 630 that have an odd number of divisors.

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Answer:

Collection of numerical information is called Statistics

Step-by-step explanation:

From the Oxford dictionary, the definition of statistics (science) is: "the practice or science of collecting and analyzing numerical data in large quantities, especially to infer proportions in a whole from those in a representative sample".

While the definition of statistic (data) is: "a fact or piece of data obtained from a study of a large quantity of numerical data".

Statistics is a science, not a method, therefore answer can´t be a).

Not all sample data is necessarily a statistic, therefore answer can´t be b).

All statistics are numerical information.

Not all statistics are population data, therefore answer can´t be d).

Cleaned data is information filtered with a specific criterion, but not necessarily used in a statistic.

The most probable answer is c.