The difference in the means is not significant because a difference of 1 is very likely is true option describing this group of 20 who sprints in two different groups each having 10 members.
The mean is the average value which can be calculated by dividing the sum of observations by the number of observations.
There are two groups, each consisting of 10 members.
Group A which consists of 10 members, has warmed up for 10 minutes.
Warming up before running will make the runners run for a longer time and run fast if they are running for a shorter duration of time.
Now,
Mean for the warm-up group = 10.9 seconds
Mean for other groups = 11.9 seconds
The difference in mean of the two groups = 11.9-10.9 = 1
Now, To test the difference in means she re-randomized the data 54 times, and the differences are plotted in the dot plot below.
As, the difference of mean = 1, which occurs for a maximum of 12 times.
As the difference in means is not too large.
So, in option A The difference in the means is not significant because a difference of 1 is very likely is true option describing this group of 20 who sprints in two different groups each having 10 members.
Learn more about mean here;
https://brainly.com/question/17060266