Refer to Exercise 12-19. Find a 90% confidence interval for the difference in the mean effectiveness of program 1 and the average of that using programs 2 and 3.

Exercise 12-19

Three training programs are being considered for auditors in an accounting firm. The success of the training programs is measured on a rating scale from 0 to 100, with higher values indicating a desirable program. The company has categorized its auditors into three groups, depending on their number of years of experience. Three auditors are selected from each group and are randomly assigned to the training programs. Table 12-40 shows the ratings assigned to the auditors after they completed the training program.

• (a) Is there a difference in the training programs as indicated by the mean evaluation scores? Test at the 10% level of significance.
• (b) Find a 90% confidence interval for the difference in the mean evaluation scores of training programs 1 and 3. Is there a difference between these two programs?