3. A simple random sample of 70 customers is taken from a customer information

file and the average age is 36. The population standard deviation is unknown.

Instead the sample standard deviation s is also calculated from the sample and is

found to be 4.5.

a. Test the hypothesis that the population mean age is greater than 33 using

the critical value approach and a 0.05 level of significance.

b. Test the hypothesis that the population mean age is less than 38 using the

p-value approach and a 0.05 level of significance.

c. Test the hypothesis that the population mean age is different from 32

using the p-value approach and a 0.05 level of significance.

4. The proportion of customers who are completely satisfied in a recent satisfaction

survey of 300 customers at XYC Inc. is found to be 0.26.

a. Test the hypothesis that the population proportion of customers who are

completely satisfied is greater than 0.22 using the critical value approach

and a 0.05 level of significance.

b. Test the hypothesis that the population proportion of customers who are

completely satisfied is less than 0.30 using the p-value approach and a

0.05 level of significance.

c. Test the hypothesis that the population proportion of customers who are

completely satisfied is different from 0.24 using the p-value approach and

a 0.05 level of significance.