Last name and acquisition timing. Refer to the Journal of Consumer Research (Aug. 2011) study of the last name effect in acquisition timing, Exercise 9.14 (p. 476). Recall that the mean response times (in minutes) to acquire basketball tickets were compared for two groups of MBA students:

those students with last names beginning with one of LO5 the first 9 letters of the alphabet and those with last names beginning with one of the last 9 letters of the alphabet.

How many MBA students from each group would need to be selected to estimate the difference in mean times to within 2 minutes of its true value with 95% confidence?

(Assume equal sample sizes will be selected for each group and that the response time standard deviation for both groups is s ≈ 9 minutes.)