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 of a particular player was 105 miles per hour (mph) and the standard deviation of the serve speeds was 9 mph. If nothing is known about the shape of the distribution, give an interval that will contain the speeds of at least eight-ninths of the player's serves.
A) 69 mph to 141 mph
B) 132 mph to 159 mph
C) 78 mph to 132 mph
D) 87 mph to 123 mph

Question

Quizplus · Accepted Answer

Using Chebyshev's theorem, at least 8/9 of the data lies within 3 standard deviations from the mean. The interval is 105 ± 3(9), which is 78 mph to 132 mph.

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