1.A simple random sample of size n is drawn from a population that is known to be normally distributed. The samplevariance, s2, is determined to be 12.1. Complete parts(a) through(c).

(a) Construct a90% confidence interval for 2 if the samplesize, n, is 20.

The lower bound is

nothing

. (Round to two decimal places asneeded.)

2.The following data represent the pH of rain for a random sample of 12 rain dates in a particular region. A normal probability plot suggests the data could come from a population that is normally distributed. A boxplot indicates there are no outliers. The sample standard deviation is s=0.325. Construct and interpret a 99% confidence interval for the standard deviation pH of rainwater in this region.

4.51

5.09

5.09

4.87

4.74

4.78

5.72

4.84

5.14

4.72

4.64

4.65

LOADING...

Click the icon to view the table of critical values of thechi-square distribution.

Select the correct choice below and fill in the answer boxes to complete your choice.

(Use ascending order. Round to three decimal places asneeded.)

A.

If repeated samples aretaken, 99% of them will have the sample standard deviation between

nothing

and

nothing

.

B.

There is a 99% probability that the true population standard deviation is between

nothing

and

nothing

.

C.

There is 99% confidence that the population standard deviation is between

nothing

and

nothing

.3.he following data represent the age(in weeks) at which babies first crawl based on a survey of 12 mothers. The data are normally distributed and s=10.107 weeks. Construct and interpret a 99% confidence interval for the population standard deviation of the age(in weeks) at which babies first crawl.

53

29

42

37

39

25

47

36

56

27

39

28

LOADING...

Click the icon to view the table of critical values of thechi-square distribution.

Select the correct choice below and fill in the answer boxes to complete your choice.

(Use ascending order. Round to three decimal places asneeded.)

A.

There is 99% confidence that the population standard deviation is between

nothing

and

nothing

.

B.

There is a 99% probability that the true population standard deviation is between

nothing

and

nothing

.

C.

If repeated samples aretaken, 99% of them will have the sample standard deviation between

nothing

and

nothing

.