The following table gives the scores of 30 students in a mathematics examination. Scores 90–99 80–89 70–79 60–69 50–59 Students 3 7 12 4 4 Find the mean and the standard deviation of the given data. Hint: Assume that all scores lying within a group interval take the middle value of that group. (Round your answers to two decimal places.)

Answers

Answer 1
The given data is
Scores:      90-99  80-89  70-79  60-69  50-59
Students:   3          7           12        4          4
Because we are to take the middle value for each group.
Therefore the total score is
Sx = 3*94.5 + 7*84.5 + 12*74.5 + 4*64.5 + 4*54.5 = 2245
The number of students is 3+7+12+4+4 = 30

The mean is
m =2245/30 = 74.833

Calculate (Sx - m)² 
(Sx - m)² = 3*(94.5-74.833)² + 7*(84.5-74.833)² + 12*(64.5-74.833)²
               + 4*(64.5-74.833)² + 4*(54.5-74.833)² =  3896.7

Calculate the standard deviation
s = √(3896.7/29) = 11.592

Answer:
mean = 74.83
std. deviation = 11.59

Related Questions

When Milo got promoted at work he received a 20% pay raise. He now earns $72,000 a year. What was his annual salary before the raise?

Answers

$57600 is the answer. 72,000 times 0.8=57600

Chen is checking a division problem by doing the following:

152
× 4
______

+ 2
______

What problem is Chen checking?

Answers

That "+2" is the remainder of a division.  Note that 152 times 4 is 608.
Dividing 608 by 4 results in 152 with no remainder.
Dividing 610 by 4 results in 152 with the remainder 2.
                                                                   ____
Chen is checking the division problem  4 /  610   .

What is the volume of a rectangular prism that has the height of 3 in in base of 14 square inches

Answers

Volume= height x area of base
Volume= 3 x 14= 42 cube inches
You know?

Sarah bought a shirt on sale for $35 the original price of the shirt was 3 times that amount sarah also bought a pair of shoes on sale for $28 the original price of the shoes was 5 times that amount together how much money did the shirt and shoes cost before they went on sale

Answers

To find the original price of the shirt:
35*3=105

To find the original price of the shoes:
28*5=140

To find the total amount of money the shirt and shoes cost before they went on sale:
105+140=145

There's your answer.

Remember: realistically, there would be sales tax, so this wouldn't be the exact amount of money they would be paying.

soymeal is 14 percent protein cornmeal is 7 percent protein how many pounds of each should be mixed together in order to get 280-lb mixture that is 9 percent protein

Answers

Let the weight of soymeal be s, and let the weight of cornmeal be c.
You need a total of 280 lb, so that gives us one equation.

s + c = 280

Now we use the protein to write another equation.
The protein in s lb of soymeal is 0.14s.
The protein in c lb of cornmeal is 0.07c.
The protein in 280 lb of 0.09% protein mix is 0.09(280).
This gives us a second equation.

0.14s + 0.07c = 0.09(280)

Now we solve the two equations as a system of equations.

s + c = 280
0.14s + 0.07c = 0.09(280)

Solve the first equation for s and plug in tot eh second equation.

s = 280 - c

0.14(280 - c) + 0.07c = 25.2

39.2 - 0.14c + 0.07c = 25.2

-0.07c = -14

c = 200

Now we substitute c = 200 in the first equation to find s.

s + 200 = 280

s = 80

Answer: 200 lb of soymeal and 80 lb of cornmeal

Can you help me please.........................

Answers

area of shaded figure = l x w = 24 *18 = 432

 area of white square =  12*12 = 144

 area of shaded part = 432-144 = 288 m^2


Answer is A

point slope for (3,21) and (6,12)

Answers

[tex]\bf \begin{array}{lllll} &x_1&y_1&x_2&y_2\\ % (a,b) &({{ 3}}\quad ,&{{ 21}})\quad % (c,d) &({{ 6}}\quad ,&{{ 12}}) \end{array} \\\\\\ % slope = m slope = {{ m}}= \cfrac{rise}{run} \implies \cfrac{{{ y_2}}-{{ y_1}}}{{{ x_2}}-{{ x_1}}}\implies \cfrac{12-21}{6-3}\implies \cfrac{9}{3}\implies 3 \\\\\\ % point-slope intercept \stackrel{\textit{point-slope form}}{y-{{ y_1}}={{ m}}(x-{{ x_1}})}\implies y-21=3(x-3)[/tex]

can 0.91919191 be written as a fraction?

Answers

Final answer:

Yes, 0.91919191 can be written as a fraction. The fraction form is 91919191/9999999.

Explanation:

Yes, 0.91919191 can be written as a fraction. To convert a repeating decimal to a fraction, we can use the following steps:

Let x be the repeating decimal.Multiply both sides of the equation x = 0.91919191... by a power of 10 that moves the decimal point to the right of the repeating part (8 digits in this case): 10000000x = 91919191.91919191...Subtract the original equation (x) from the new equation (10000000x) to eliminate the repeating part: 10000000x - x = 91919191.91919191... - 0.91919191...Simplify the equation: 9999999x = 91919191Divide both sides of the equation by 9999999 to solve for x: x = 91919191/9999999

Therefore, 0.91919191 can be written as the fraction 91919191/9999999.

Kai picked 11 times as many blueberries as Nico. Together, they picked 936 blueberries. how many blueberries did each boy pick?

Answers

11x+x=936
12x=936
x=78
Nico picked 78.
78*11= 858
Kai picked 858.

Answer: Number of blueberries picked by Nico =78

Number of blueberries picked by Kai =858

Step-by-step explanation:

Given : Kai picked 11 times as many blueberries as Nico.  

Let , Number of blueberries picked by Nico =x

Then, Number of blueberries picked by Kai = 11x

Together, they picked 936 blueberries.

[tex]\Rightarrow\ x+11x=936\\\\\Rightarrow\ 12x=936\\\\\Rightarrow\ x=\dfrac{936}{12}=78[/tex]

Now, Number of blueberries picked by Nico =78

Then, Number of blueberries picked by Kai = 11(78) =858

The number of surface flaws in plastic panels used in the interior of automobiles has a poisson distribution with a mean of 0.05 flaw per square foot of plastic panel. assume an automobile interior contains 10 square feet of plastic panel. (a) what is the probability that there are no surface flaws in an auto's interior? (b) if 10 cars are sold to a rental company, what is the probability that none of the 10 cars has any surface flaws? (c) if 10 cars are sold to a rental company, what is the probability that at most one car has any surface flaws?

Answers

Given that the number of surface flaws in plastic panels used in the interior of automobile has a Poisson distribution with a mean of 0.05 flaws per square foot of plastic panel. The number of surface flaws(X) in an automobile interior is also Poisson random variable with a mean of 10 x 0.05 = 0.5. The probability that there are no surface flaws in an auto's interior, P(X = 0) = (e^-0.5 (0.5)^0 / x!) = e^-0.5 = 0.6065

What's the answer to find y when x=9 if y varies directly as the square of x ,and y =100 when x= 5

Answers

"y varies directly with square of x"
y = kx²
where "k" is the constant of variation you need to solve for first.

when y = 100 ; x = 5
100 = k(5)²
100 = 25k
100/25 = k
4 = k

Now you can solve for y when x = 9
y = 4(9)²
y = 4(81)
y = 324

Ratio equivalents to 1:2

Answers

2:4  3:6  4:8

Any ratio equals 1:2 as long as you can divide the first number by itself to get 1 and the second number with the 1st number.
Example
2:4
Divide the first number by 2 and you get 1 
Divide the second number by 2 and you get 2
So the ratio equals 1:2


Please make me brainliest
Some ratios that are equivalent to 1:2 include

2:4
3:6
4:8
5:10

and so on and so forth
hope this helps

On a survey mission,a pilot flew out to a parcel of land and back in 7h. The rate flying out was 120mph. The rate flying back was 90mph.how far away was the parcel of

Answers

The answer is 750 mph
Final answer:

To find the distance, multiply the speed by the time for each leg of the trip and add them together to get the total distance of 735 miles.

Explanation:

To find the distance to the parcel of land, we can use the formula Distance = Speed x Time. Since the pilot flew out and back, we can calculate the distance for each leg of the trip and then add them together.

Distance going out = Speed x Time = 120 mph x (7/2) hours = 420 miles

Distance coming back = Speed x Time = 90 mph x (7/2) hours = 315 miles

Total distance = Distance going out + Distance coming back = 420 miles + 315 miles = 735 miles

There is 1/4 ounce of yeast in every 2 1/4 teaspoons of yeast. A recipe for bread calls for 2 teaspoons of yeast. How many ounces of yeast are needed for this ecipe

Answers

Here is the set up:

(1/4)/2 = (9/4)/y

Solve for y.

(b) what is the probability that more than eleven loads occur during a 4-year period

Answers

In a 4-year period, expect around 2 loads (Poisson model). Over 11 loads is likely (80% chance). No loads for 5.8 years or more guarantees under 30% chance.

In a Poisson process with a mean time between occurrences of λ = 0.4 years, we can answer your questions as follows:

**(a) Expected number of loads in 4 years:**

The expected number of events in a Poisson process is the product of the mean occurrence rate (λ) and the time interval (t). Therefore, in a 4-year period, you can expect:

Expected loads = λ * t = 0.4 years/load * 4 years ≈ 1.6 loads

However, since the Poisson process deals with discrete events, the expected value doesn't necessarily translate to an exact number of occurrences. It represents the average number of loads you would expect to see over many repetitions of the same 4-year period.

**(b) Probability of more than 11 loads in 4 years:**

To calculate the probability of more than 11 loads, we need to find the probability of 12 or more loads. In a Poisson process, the probability of k events occurring in a time interval t is given by:

P(k events) = (e^(-λt) * (λt)^k) / k!

For k = 12 and λt = 4 * 0.4 = 1.6:

P(more than 11 loads) = 1 - P(0 loads) - P(1 load) - ... - P(11 loads)

≈ 1 - (e^(-1.6) * 1.6^0) / 0! - (e^(-1.6) * 1.6^1) / 1! - ... - (e^(-1.6) * 1.6^11) / 11!

≈ 1 - 0.1995 ≈ 0.8005

Therefore, the probability of having more than 11 loads in a 4-year period is approximately 0.801 (rounded to three decimal places).

**(c) Time period for at most 0.3 probability of no loads:**

We want to find the time period (t) where the probability of no loads (P(0 loads)) is at most 0.3. In other words, we need to solve:

P(0 loads) = e^(-λt) ≤ 0.3

Taking the natural logarithm of both sides and rearranging:

t ≥ -ln(0.3) / λ ≈ 2.303 / 0.4 ≈ 5.76 years

Therefore, the time period must be at least 5.76 years (rounded to four decimal places) for the probability of no loads to be at most 0.3.

The probable question may be:

An article suggests that a Poisson process can be used to represent the occurrence of structural loads over time. Suppose the mean time between occurrences of loads is 0.4 year.

(a) How many loads can be expected to occur during a 4-year period?

(b) What is the probability that more than eleven loads occur during a 4-year period? (Round your answer to three decimal places.)

(c) How long must a time period be so that the probability of no loads occurring during that period is at most 0.3? (Round your answer to four decimal places.)

Abby did 121 sit ups in 8 minutes .estimate the number of sit-ups she did in 1 minute.

Answers

Isnt the answer 15? I think so
I thank the the answer is 15r1. That's what is got

calculate gas mileage of car that drives 283 miles on 12.3 gallons of gas andround to nearest tenth of a mpg

Answers

283 divided by 12.3 = 23.008 and rounded it will just be 23.
Final answer:

The gas mileage of a car that drives 283 miles on 12.3 gallons of gas is approximately 23.0 miles per gallon, when rounded to the nearest tenth.

Explanation:

Gas mileage is determined by dividing the total miles driven by the gallons of gas consumed. In this scenario, 283 miles were covered using 12.3 gallons of gas. The calculation yields approximately 22.97 miles per gallon (mpg), but rounding to the nearest tenth results in 23.0 mpg. This figure represents the efficiency of the vehicle in terms of fuel consumption, offering a quick and easy measure for assessing its economic and environmental impact. Monitoring gas mileage is crucial for budgeting and understanding the ecological footprint of transportation choices, promoting conscientious and efficient use of fuel resources.

Learn more about Gas Mileage here:

https://brainly.com/question/33812030

#SPJ12

What is 121,356 rounded to the nearest 10,000? Is it 120,000?

Answers

Yes, you are correct. The answer would be 120,000.

Last question please that I need

Answers

The proper perpendicular slope should be -1/4 instead of positive 1/4. The y intercept is also incorrect

Let's call the y intercept b for now
m = -1/4 is the perpendicular slope
(x,y) = (16,1) is the point the perpendicular line goes through
breaking this down further means x = 16 and y = 1 pair up together

y = mx+b
y = (-1/4)*x+b ... replace m with -1/4
y = (-1/4)*16+b .... replace x with 16
1 = (-1/4)*16+b .... replace y with 1
1 = -4+b ... multiply -1/4 and 16 to get -4
1+4 = -4+b+4 ... add 4 to both sides
5 = b
b = 5
So the y intercept is 5 (not 4)

since m = -1/4 and b = 5  we go from 
y = mx+b
to
y = (-1/4)x+5

So the final answer is y = (-1/4)x+5 which can be written as [tex]y = -\frac{1}{4}x+5[/tex]

As a check, we can plug x = 16 into the equation to get...
y = (-1/4)*x + 5
y = (-1/4)*16 + 5
y = -4 + 5
y = 1
so that confirms we have the right answer.

The model represents an equation. What value of x makes the equation true?

A)
2


B)
4
7


C)
−2


D)

4
7

Answers

It would be x= -4/7......

if the coefficient of determination for a data set is 0.25 and the SSE for the data set is 24, what is the SST for the data set?

Answers

Answer:  SST for the data set is 32.

Step-by-step explanation:

Since we have given that

Coefficient of determination = R² = 0.25

Value of SSE = 24

We need to find SST.

As we know the formula for "Coefficient of determination":

[tex]R^2=1-\dfrac{SSE}{SST}[/tex]

We will put the above mentioned value:

[tex]0.25=1-\dfrac{24}{SST}\\\\0.25-1=-\dfrac{24}{SST}\\\\-0.75=-\dfrac{24}{SST}\\\\SST=\dfrac{24}{0.75}\\\\SST=32[/tex]

Hence, SST for the data set is 32.

Which ordered pair comes from the table?

X Y
2 1
3 4
4 4
5 2

A. (1,2)
B. (4,3)
C. (2,1)
D. (2,5)

Answers

The only (x, y) ordered pair in the table is ...
  C. (2, 1)

Answer:

Option C is correct

(2, 1) ordered pair comes from the table

Step-by-step explanation:

Ordered pair  states that an ordered pair contains the coordinate of points in the coordinate plane in the form of (x, y)

Given the table:

X Y  

2 1  

3 4

4 4

5 2

Ordered pairs for this table are:

From the definition, we have;

(2, 1), (3, 4), (4, 4) and (5, 2)

Therefore, the only ordered pairs comes from the table is, (2, 1)

write the numerical expression in words then solve (98-78)×11

Answers

Find the difference between ninety-eight and seventy-eight, then multiply by eleven. Ninety-eight minus seventy-eight is twenty, take this and multiply if by eleven to arrive at an answer of eleven. Following the order of operations the math within the parentheses must be done first, then the multiplication. The answer is two-hundred and twenty.

Solve for w . =−40−w6 Simplify your answer as much as possible.

Answers

Assuming that the left side of the equation is equal to zero, w=6.667

Let x be the number of successes throughout n independent repetitions of a random experiment having probability of success p=1/4. determine the smallest value of n so that p(1<=x)>=0.7

Answers

To answer problems like this you have to use binomial:

P (x > 1) = 1 – p (0 < x < 1) > .7 

So:

1 – p (0) – p (1) > .7 

1 – (3/ 4) ^n – (3/ 4) ^n (n – 1 ) (1/ 4) > .7 

Therefore n > 5.185, and the smallest value of n so that we can satisfy the given condition is 6 (rounded up)

 

The least squares method is a mathematical procedure used to identify the linear equation that best fits a set of ordered pairs.
a. True
b. False

Answers

This is true, answer a.

Evaluate xe^(x^2+y^2+z^2) where e is the portion of the unit ball x^2+y^2+z^2 < 1 that lies in the firat octant

Answers

Given

[tex]\int\int\int_E xe^{(x^2+y^2+z^2)}[/tex]

where E is the portion of the unit ball [tex]x^2+y^2+z^2\leq1[/tex] that lies in the first octant.

This can be evaluated as follows:

[tex]\int_0^1\int_0^{\sqrt{1-x^2}}\int_0^{\sqrt{1-x^2-y^2}} xe^{(x^2+y^2+z^2)}dzdydx=0.392699[/tex]

the tree in Debra backyard is 7.5m high. how high is it in centimeters

Answers

Hello! 100 centimeters equal 1 meter. In this case, to find the amount of centimeters, you have to do 100 * 7.5. When you do that, you get 750. The tree in Debra’s backyard is 750 centimeters high.

choose the ratio that you would use to convert 5.5 pounds to ounces

Answers

We want "pounds" to disappear, in favor of "ounces."

Thus, multiply 5.5 pounds by (16 oz / 1 pound).  "pounds" cancels, leaving you with "88 oz."  

Answer:

A. 16 ounces/1 pound

Step-by-step explanation:

Remember that: 1 pound (lb) is equal to 16 Ounces (oz).

Then you have to find a ratio to convert 5.5 pounds to ounces.

If you write: 5.5 pounds, you have to find a ratio that eliminates pounds in order to get ounces:

5.5 pounds*16 ounces/1 pound

In this way pounds in the numerator is eliminated with pounds from the denominator and the result you get is in units of ounces.

5.5 pounds*16 ounces/1 pound=88 ounces

Helen rented a kayak at the lake. There is a charge of $6 as an initial fee and then $3 an hour for every hour that she uses the kayak. If the total charge is $21, how many hours did she kayak?

Answers

Helen kayaked for 5 hours.
Hope this helps!!
5 hours is your answer
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