10.56 Internet book prices Anna’s project for her introductory statistics course was to compare the selling prices of textbooks at two Internet bookstores. She first took a random sample of 10 textbooks used that term in courses at her college, based on the list of texts compiled by the college bookstore. The prices of those textbooks at the two Internet sites were Site A: $115, $79, $43, $140, $99, $30, $80, $99, $119, $69 Site B: $110, $79, $40, $129, $99, $30, $69, $99, $109, $66

a. Are these independent samples or dependent samples?

Justify your answer.

b. Find the mean for each sample. Find the mean of the difference scores. Compare and interpret.

c. Using software or a calculator, construct a 90%

confidence interval comparing the population mean prices of all textbooks used that term at her college.

Interpret.