18. Five people who were convicted of speeding were ordered by the court to attend a workshop. A special device put into their cars kept records of their speeds for two weeks before and after the workshop. The maximum speeds for each person during the two weeks before and the two weeks after the workshop follow.

Participant Before After L. B. 65 58 J. K. 62 65 R .C. 60 56 R. T. 70 66 J. M. 68 60 Using the .05 significance level, should we conclude that people are likely to drive more slowly after such a workshop?

(a) Use the steps of hypothesis testing.

(b) Sketch the distributions involved.

(c) Explain your answer to someone who is familiar with hypothesis testing involving known populations, but has never learned anything about t tests.