11 Runners Are Timed at the 100-Meter Dash and Are

Essay

11 runners are timed at the 100-meter dash and are timed again one month later after following a new training program. The times (in seconds)are shown in the table. Use a significance level of 0.05 to test the claim that the training has no effect on the times. $\begin{array}{ll}\text { Before } & 12.1&12 .4&11 .7&11 .5&11 .0&11 .8&12 .3&10 .8&12 .6&12 .7&10 .7 \\\hline \text { After } & 11.9&12 .4&11 .8&11 .4&11 .2&11 .5&12 .0&10 .9&12 .01&2 .2&11 .1\end{array}$