If you need to estimate the population mean within 2.5 units and with a confidence level of 95%, the minimum value observed is 15 and the maximum 65. What sample size would you use?
A) 9
B) 10
C) 81
D) 96
E) 97

Question

Quizplus · Accepted Answer

To estimate the sample size, we use the formula for the sample size of a mean: n = (Z * σ / E)^2. With a 95% confidence level, Z is 1.96. The range (65-15) is 50, so an approximate standard deviation (σ) is 50/4 = 12.5. The margin of error (E) is 2.5. Plugging these into the formula gives n = (1.96 * 12.5 / 2.5)^2 ≈ 96.04, which rounds up to 97.

If You Need to Estimate the Population Mean Within 2