The diameters of ball bearings produced in a manufacturing process can be described using a uniform distribution over the interval 2.5 to 4.5 millimeters. Any ball bearing with a diameter of over 4.25 millimeters or under 2.75 millimeters is considered defective. What is the probability that a randomly selected ball bearing is defective?
A) .25
B) .50
C) .75
D) 0

Question

Quizplus · Accepted Answer

The interval of non-defective ball bearings is from 2.75 to 4.25 millimeters. The total interval is 2.5 to 4.5 millimeters, which is 2 millimeters wide. The non-defective interval is 1.5 millimeters wide (4.25 - 2.75). The probability of a ball bearing being non-defective is 1.5/2 = 0.75, so the probability of being defective is 1 - 0.75 = 0.25.

The Diameters of Ball Bearings Produced in a Manufacturing Process