10.
83 random samples were selected from a normally distributed population and were found to have a mean of 32.1 and a standard deviation of 2.4. Construct a 90% confidence interval for the population standard deviation.

A.
2.2 < σ < 2.8

B.
28.8 < σ < 37.4

C.
4.6 < σ < 7.8

D.
1.4 < σ < 1.8

Now we just take square root on both sides of the interval and we got:

And the best option would be:

A.  2.2 < σ < 2.8

Step-by-step explanation:

Information provided

represent the sample mean

population mean  

s=2.4 represent the sample standard deviation

n=83 represent the sample size  

Confidence interval

The confidence interval for the population variance is given by the following formula:

The degrees of freedom are given by:

The Confidence is given by 0.90 or 90%, the value of and , the critical values for this case are:

And replacing into the formula for the interval we got:

Now we just take square root on both sides of the interval and we got:

And the best option would be:

A.  2.2 < σ < 2.8

21.4 i did it already for s1

step-by-step explanation:

fist on the left goes with the third on the right. second on the left goes with the fourth on the right. third on the left goes with the second on the right. the fourth on the left goes with first on the right