2. A day after, the 13 students mentioned in problem 1 takes the same test a second time. This time their scores were: 10, 10, 10, 10, 11, 13, 19, 9, 9, 8, 1, 7, 8.

a. Find the mean.

b. Find the median

c. Find the mode.

d. Was there a difference in their performance when taking the test a second time?​