The diameters of bolts produced by a certain machine are normally distributed with a mean of 0.30 inches and a standard deviation of 0.01 inches. What percentage of bolts will have a diameter greater than 0.32 inches?
A) 2.28%
B) 37.45%
C) 47.72%
D) 97.72%

Question

Quizplus · Accepted Answer

The z-score for a diameter of 0.32 inches is (0.32 - 0.30) / 0.01 = 2. A z-score of 2 corresponds to the 97.72 percentile, meaning 97.72% of bolts have a diameter less than 0.32 inches. Therefore, 100% - 97.72% = 2.28% of bolts have a diameter greater than 0.32 inches.

The Diameters of Bolts Produced by a Certain Machine Are