Some college professors make bound lecture notes available to their classes in an effort to improve teaching effectiveness. In a study, two groups of students were surveyed –86 students enrolled in a promotional strategy class that required the purchase of lecture notes and 35 students enrolled in a sales/retailing elective that did not offer lecture notes. At the end of the semester, students were asked to respond to the statement, "Having a copy of the lectrure notes was (would be) helpful in understanding the material." Responses were measured on a 9-point semantic difference scale, where 1=strongly disagree and 9=strongly agree. A summary of the results is reported in the follow:

Classes Buying Lecture Notes Classes Not Buying Lecture Notes

n1=86 n2=35

X1=8.48 X2=7.80

S21=.94 S22=2.99

a. Describe the two populations involved in the comparison.

b. Do the samples provides sufficient evidence to conclude that there is a difference in the mean responses of the two groups of the students? Test using α=.01

c. Construct a 99% confidence interval for (μ1-μ2). Interpret the result.

d. Would a 95% confidence interval for (μ1-μ2) be narrow or wider than the one you found in part c? Why?