Question

The distribution of a sample of the outside diameters of PVC gas pipes approximates a symmetrical, bell-shaped distribution. The arithmetic mean is 11.0 inches, and the standard deviation is 2.0 inches. About 68 percent of the outside diameters lie between what two amounts?
8.5 and 12.0 inches
12.0 and 13.0 inches
10.0 and 12.5 inches
9.0 and 13.0 inches

Answer 1

(11.0-2.0, 11.0+ 2.0)
(9.0 , 13.0)
9.0 and 13.0 inches

Answer 2

Thanks again!!