The distribution of a sample of the outside diameters of PVC pipes approximates a symmetrical,bell-shaped distribution. The arithmetic mean is 14.0 inches,and the standard deviation is 0.1 inches. About 68% of the outside diameters lie between what two amounts?
A)13.5 and 14.5 inches
B)13.0 and 15.0 inches
C)13.9 and 14.1 inches
D)13.8 and 14.2 inches

Question

Quizplus · Accepted Answer

According to the empirical rule, approximately 68% of the data falls within one standard deviation of the mean. Since the standard deviation is 0.1 inches and the mean is 14.0 inches, one standard deviation below the mean is 13.9 inches and one standard deviation above the mean is 14.1 inches. Therefore, about 68% of the outside diameters lie between 13.9 and 14.1 inches.

The Distribution of a Sample of the Outside Diameters of PVC