Ball-Bearings, Inc. produces ball bearings automatically on a Kronar BBX machine. For one of the ball bearings, the mean diameter is set at 20.00 mm (millimetres). The standard deviation of the production over a long period of time was computed to be 0.150 mm. What percent of the ball bearings will have diameters 20.27 mm or more?
A) 41.00%
B) 12.62%
C) 3.59%
D) 85.00%
E) None of the choices are correct

Question

Quizplus · Accepted Answer

To find the percentage of ball bearings with diameters 20.27 mm or more, we calculate the z-score: z = (20.27 - 20.00) / 0.150 = 1.8. Using the standard normal distribution table, the probability of a z-score less than 1.8 is approximately 0.9641. Therefore, the probability of a z-score of 1.8 or more is 1 - 0.9641 = 0.0359, or 3.59%.