A simple random sample of 80 customers is taken from a customer information file and the average age is 34. The population standard deviation is...

A simple random sample of 80 customers is taken from a customer information file and the average age is 34. The population standard deviation σ is unknown. Instead the sample standard deviation s is also calculated from the sample and is found to be 5.5. (6 points)

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