Twenty-four 9th- and 10th-grade high school girls were put on an ultra-heavy rope-jumping program. The following data give the time difference for each girl (€œbefore program time€ minus €œafter program time€) for the 40-yard dash:

(a) Give a point estimate of μD, the mean of the difference in race times.
(b) Find a one-sided 95% confidence interval that is a lower bound for μD.
(c) Does it look like the rope-jumping program was effective?

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0.28 0.01 0.13 0.33 -0.03 0.07 -0.18 -0.14 -0.33 0.01 0.22 0.29 -0.08 0.23 0.08 0.04 -0.30-0.08 0.09 0.70 0.33 0.34 0.50 0.06