Sales commissions: A company studied two programs for compensating its sales staff. Nine salespeople participated in the study. In program A, salespeople were paid a higher salary, plus a small commission for each item they sold. In program B, they were paid a lower salary with a larger commission. Following are the amounts sold, in thousands of dollars, for each salesperson on each program.

Can you conclude that the mean sales differ between the two programs?
Use the α = 0.05 level of significance.

Salesperson Program 1 2 3 4 5 6 7 8 9 AB A 55 22 34 22 25 61 55 36 68 B 53 24 36 28 31 61 58 38 72