The cost of a university education has increased at a much faster rate than costs in general over the past twenty years. In order to compensate for this, many students work part- or full-time in...

The cost of a university education has increased at a much faster rate than costs in general over the past twenty years. In order to compensate for this, many students work part- or full-time in addition to attending classes. At one university, it is believed that the average number of hours students work per week exceeds 20. A random sample of 20 students was selected and the following values were observed:

1. The correct value of the test statistic is