question 28

The waiting times (in minutes) of a random sample of

20

people at a bank have a sample standard deviation of

4.9

minutes. Construct a confidence interval for the population variance

2

and the population standard deviation

.

Use a

90%

level of confidence. Assume the sample is from a normally distributed population.

What is the confidence interval for the population variance

2?

(nothing,nothing)

(Round to one decimal place as needed.)

Interpret the results. Select the correct choice below and fill in the answer box(es) to complete your choice.

(Round to one decimal place as needed.)

A.

With

10%

confidence, you can say that the population variance is between

___

and

____

B.

With

90%

confidence, you can say that the population variance is

greater

than

____

C.

With

90%

confidence, you can say that the population variance is between

___

and ___

D.

With

10%

confidence, you can say that the population variance is

less

than

____

What is the confidence interval for the population standard deviation

?

(nothing,nothing)

(Round to one decimal place as needed.)Interpret the results. Select the correct choice below and fill in the answer box(es) to complete your choice.(Round to one decimal place as needed.)

A.

With

90%

confidence, you can say that the population standard deviation is between

____

and

____

minutes.

B.

With

10%

confidence, you can say that the population standard deviation is between

____ minutes and

____

minutes.

C.

With

10%

confidence, you can say that the population standard deviation is

greater

than

___

minutes.

D.

With

90%

confidence, you can say that the population standard deviation is

less

than

____

minutes.

question 30

Assume that male and female births are equally likely and that the birth of any child does not affect the probability of the gender of any other children. Find the probability of exactly

two

boys in ten births. Round the answer to the nearest thousandth.

A.

0.044

B.

0.020

C.

11.250

D.

0.200

question 31

The stem-and-leaf plot of weights (in pounds) of carry-on luggage on a plane is shown below. Find the mean, median, and mode of the data. If any measure cannot be found or does not represent the center of the data, explain why.

1	0 2	Key: 1 | 0 = 10
2	1 4 9 9
3	7 8
4	3 5 5
5	0 7
6	5
7
8
9
10	4

Find the mean. Select the correct choice below and, if necessary, fill in the answer box to complete your choice.

A.

The mean is

nothing.

(Type an integer or decimal rounded to one decimal place as needed.)

B.

There is no mean for this data set.

Does the mean represent the center of the data?

A.

The mean represents the center.

B.

The mean does not represent the center because it is not a data value.

C.

The mean does not represent the center because it is the largest data value.

D.

The mean does not represent the center because it is the smallest data value.

E.

The data set has no mean because the data values are at the nominal level of measurement.

Find the median. Select the correct choice below and, if necessary, fill in the answer box to complete your choice.

A.

The median is

(Type an integer or decimal rounded to one decimal place as needed.)

B.

There is no median for this data set.

Does the median represent the center of the data?

A.

The median represents the center.

B.

The median does not represent the center because it is the largest data value.

C.

The median does not represent the center because it is not a data value.

D.

The median does not represent the center because it is the smallest data value.

E.

The data set has no median because the data values are at the nominal level of measurement.

Find the mode(s). Select the correct choice below and, if necessary, fill in the answer box to complete your choice.

A.

The mode(s) is/are

(Type an integer or decimal rounded to one decimal place as needed. Use a comma to separate answers as needed.)

B.

There is no mode for this data set.

Does (Do) the mode(s) represent typical, or central, data entries?

A.

Yes, the mode(s) represent(s) typical data entries.

B.

The mode(s) does (do) not represent typical data entries because it (they) is (are) not a data value.

C.

The mode(s) does (do) not represent typical data entries because it (one) is the largest data value.

D.

The mode(s) does (do) not represent typical data entries because it (one) is the smallest data value.

E.

The data set has no mode because the data values are at the nominal level of measurement.

question 32

Use the value of the linear correlation coefficient to calculate the coefficient of determination. What does this tell you about the explained variation of the data about the regression line? About the unexplained variation?

r=0.443

Calculate the coefficient of determination.

(Round to three decimal places as needed.)

What does this tell you about the explained variation of the data about the regression line?

____%

of the variation can be explained by the regression line.

(Round to one decimal place as needed.)

About the unexplained variation?

____%

of the variation is unexplained and is due to other factors or to sampling error.

(Round to one decimal place as needed.)