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 104 miles per hour (mph) and the standard deviation of the serve speeds was 11 mph. If nothing is known about the shape of the distribution, give an interval that will contain the speeds of at least three-fourths of the player's serves.
A) 82 mph to 126 mph
B) 93 mph to 115 mph
C) 71 mph to 137 mph
D) 126 mph to 148 mph

Question

Quizplus · Accepted Answer

The interval that will contain the speeds of at least three-fourths of the player's serves is the mean plus or minus 1 standard deviation, which is 104 mph ± 11 mph, or 93 mph to 115 mph.

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