In a manufacturing process, we are interested in measuring the average length of a certain type of bolt. Past data indicate that the standard deviation is .25 inches. How many manufactured bolts should be sampled in order to make us 95 percent confident that the sample mean bolt length is within .02 inches of the true mean bolt length?
A) 25
B) 49
C) 423
D) 601
E) 1225

Question

Quizplus · Accepted Answer

n = [(z_α_/2 × s)/E]²= [(1.96 × .25)/.02]² = 600.25 = 601

In a Manufacturing Process, We Are Interested in Measuring the Average