The Lengths of Screws Produced by a Machine Are Normally

Multiple Choice

The lengths of screws produced by a machine are normally distributed with a mean of 3 inches and a standard deviation of .2 inches. Therefore, we know:

A) that approximately 68 percent of all screws have lengths between 2.8 and 3.2 inches
B) that approximately 95 percent of all screws have lengths between 2.8 and 3.2 inches
C) that just about all screws have lengths between 2.8 and 3.2 inches
D) that approximately 98 percent of all screws have lengths between 2.8 and 3.2 inches
E) none of these