Students attending West Valley Community College buy their textbooks online from one of two different book sellers because the college does not have a bookstore. The following data represent sample amounts that students spend on books per term:

Company 1 ($) Company 2 ($)
246 300 211 305 235 308 270 325 411 340 310 295 450 320 502 330 311 240 200 360

a. Do these data indicate a difference in mean textbook prices for the two companies? Apply the Mann–Whitney U test with a significance level of 0.10.

b. Apply the t-test to determine whether the data indicate a difference between the mean amount spent on books at the two companies. Use a significance level of 0.10. Indicate what assumptions must be made to apply the t-test.