• The population standard deviation is unknown where 80 customers are taken from a customer information file and the average age is 34. Instead the sample standard deviation s is also calculated from the sample and is found to be 5.5.

1.Test the hypothesis that the population mean age is greater than 30 using the critical value approach and a 0.05 level of significance.

2.Test the hypothesis that the population mean age is less than 37 using the p-value approach and a 0.05 level of significance.

3.Test the hypothesis that the population mean age is different from 31 using the p-value approach and a 0.05 level of significance.