A researcher conducted a study of the access speed of 45 hard drives and concluded that his maximum error of estimate was 20. If he were to conduct a second study to reduce the maximum error of estimate to 5, about how many hard drives should he include in his new sample?
A) 45
B) 90
C) 180
D) 720

Question

Quizplus · Accepted Answer

To reduce the maximum error of estimate by a factor of 4 (from 20 to 5), the sample size must be increased by a factor of 16 (since error is inversely proportional to the square root of the sample size). Thus, 45 * 16 = 720.

A Researcher Conducted a Study of the Access Speed of 45