Question

publisher wants to estimate the mean length of time​ (in minutes) all adults spend reading newspapers. To determine this​ estimate, the publisher takes a random sample of 15 people and obtains the results below. From past​ studies, the publisher assumes sigmaσ is1.9 minutes and that the population of times is normally distributed.

11

7

8

12

7

11

6

6

9

9

7

8

10

8

10

Construct the​ 90% and​ 99% confidence intervals for the population mean. Which interval is​ wider? If​ convenient, use technology to construct the confidence intervals.

1.The​ 90% confidence interval is

​ (Round to one decimal place as​ needed.)

2.The​ 99% confidence interval is

​

​ (Round to one decimal place as​ needed.)

3. Which interval is​ wider?

The​ 99% confidence interval

The​ 90% confidence interval

Answer 1

The statistical software output for this problem is :

1.The​ 90% confidence interval is

(7.7 , 9.5)

2.The​ 99% confidence interval is

(7.2 , 10.0)

3)

The​ 99% confidence interval