In the past, the average age of employees of a large corporation has been 40 years. Recently, the company has been hiring older individuals. In order to determine whether there has been an increase in the average age of all the employees, a sample of 64 employees was selected. The average age in the sample was 45 years with a standard deviation of 16 years. Let α = 0.5.

a. State the null and the alternative hypothesis. 

b. Compute the test statistic.

c. Using the critical-value approach, test to determine wether or not the mean age of all employees is significantly more than 40 years.