At the U.S. Open Tennis Championship a statistician keeps track of every serve that a player hits during the tournament. The statistician reported that the mean serve speed was 100 miles per hour
(mph)and the standard deviation of the serve speeds was 15 mph. If nothing is known about the
Shape of the distribution, what percentage of the playerʹs serve speeds are less than 70 mph?
A)approximately 2.5%
B)at most 12.5%
C)approximately 5%
D)at most 11%
E)at most 25%

Question

Quizplus · Accepted Answer

Using Chebyshev's inequality, at most 25% of the serve speeds can be more than 2 standard deviations away from the mean, which includes speeds less than 70 mph.

At the US Open Tennis Championship a Statistician Keeps Track of Every