I had figured out all the other problems but having problems with these 3 below. I have read other examples but that doesnt seem to help much. If you could Please Help.

Complete the full confidence interval procedure for each of the following.

Problem

A college administrator would like to determine how much time students spend on

homework assignments during a typical week. A questionnaire is sent to a

random sample of n =100 students and their response indicates a mean of

7.4 hours per week. The population standarddeviation is known to be 3 hours.

Construct a 95% confidence intervalfor the population mean of the number of hours student spend on homework during a typicalweek.

Problem

In Roosevelt National Forest, the rangers took random samples of live aspen trees and

measured the base circumferenceof each tree. Assume that the circumferences of the trees are

normally distributed.The average of the 100 trees sampled was 15.71. The population standard deviation is 4.63 inches. Construct a 90% confidence interval

for the population mean of the circumference of the aspen tree.

Problem

The number of hours shoppers spend at Wegman's is normally distributed. A random sample of 25 shoppers has a

sample mean of 42 minutes. The population standard deviation is 12 minutes. Construct a 99% confidence interval for

the population mean of the time shoppers spend at Wegmans.

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