The owner of a mosquito-infested fishing camp wants to test the effectiveness of two rival brands of mosquito repellents, X and Y. During the first month of the season, five people are chosen at random to take part in the experiment. For each of these guests, Brand X is randomly applied to one arm and Brand Y is applied to the other arm. These guests' fish for 4 hours, then the owner counts the number of bites on each arm. The table below shows the number of bites on the arm with Brand X and those on the arm with Brand Y for each guest.

Test at the 5% significance level whether the mean number of bites on the arm with Brand X is higher than the mean number of bites on the arm with Brand Y. (MUST USE: d = X - Y)

Guest

A

B

C

D

E

Brand X

12

23

18

36

8

Brand Y

9

20

21

27

6