Question: A study is designed to determine the effect of an office-training course on typing productivity. Ten typists are randomly selected and are asked to type 15 pages of equally difficult text before and after completing the course. Their productivity is measured by the total number of errors made.

Typist Before After Typist Before After

1 30 27 6 33 31

2 19 14 7 28 22

3 36 31 8 30 25

4 42 37 9 27 30

5 35 29 10 34 33

Assume that the total number of errors can be approximated by a normal distribution. Test the claim that taking the office-training courses leads to a reduction in the average number of errors made by a typist. Use a significance level of .05.