Carter wants to know if warming up will help runners sprint faster. Thirty track and field athletes volunteered to participate in his study. He randomly assigns 15 athletes to warm-up for 10 minutes. All 30 participants sprint the same distance. He calculates the mean for each group and determines that the mean for the warm-up group was 10.7 seconds, and the mean for the other group was 13.2 seconds. To test the difference of means he re-randomized the data 54 times, and the differences are plotted in the dot plot below. What can Carter conclude from his study?

Question

_zd3 · Answer

A dot plot is shown labeled from negative 2.5 to positive 2. Above the negative 2.5 are 3 dots. Above the negative 2 are 6 dots. Above the negative 1.5 are 9 dots. Above the negative 1 are 12 dots. Above the negative 0.5 are 6 dots. Above the 0.0 are 4 dots. Above the 0.5 are 3 dots. Above the 1.0 are 7 dots. Above the 1.5 are 3 dots. Above the 2.0 is 1 dot.
 The difference in the means is significant because a difference of 2.5 is very likely.
 The difference in the means is not significant because a difference of 2.5 is very likely.
 The difference in the means is significant because a difference of 2.5 is not very likely.
 The difference in the means is not significant because a difference of 2.5 is not very likely.