19. Returning to the previous exercise, the mean and standard deviation of the number of credit cards for the no-involvement group were 2.22 and 1.58, respectively, whereas the mean and standard deviation for the payment-help group were 2.09 and 1.65, respectively.

Does it appear that the true average number of cards for no-involvement students exceeds the average for payment-help students? Carry out an appropriate test of signi cance.