13.8 The owner of a small book-publishing company is concerned about the declining number of people who read books. To learn more about the problem she takes a random sample of customers in a retail bookstore and asked each how many books they read in the last 12 months. The following figures were recorded.

Females 5, 18, 11, 3, 7, 5, 9, 13, 15

Males 9, 7, 9, 3, 6, 5

Is there enough evidence to conclude that there are differences in the number of books purchased by females and males?