b) A histogram of the differences shows:
-7 2 **
-6 2 **
-5 3 ***
-4 9 *********
-3 13 *************
-2 23 ***********************
-1 18 ******************
0 19 *******************
1 8 ********
2 6 ******
3 1 *
The mean difference is -1.5, with a standard deviation of 2.019.
c) Attitudes towards STAT 110 seem to have improved after the first class for most students (negative differences), although there are 15 students who reported the reverse effect (positive differences).