It is desired to estimate the average time it takes Statistics students to finish a computer project to within two hours at 97% reliability. It is estimated that the standard deviation of the times is 14 hours. How large a sample should be taken to get the desired interval?
A) n = 17
B) n = 189
C) n = 231
D) n = 133

Question

Quizplus · Accepted Answer

To find the sample size, use the formula for the sample size of a mean: n = (Z * σ / E)^2. Here, Z is the z-value for 97% confidence (approximately 2.17), σ is the standard deviation (14 hours), and E is the margin of error (2 hours). Plugging these values into the formula gives n ≈ 231.

It Is Desired to Estimate the Average Time It Takes