The sample size needed to provide a margin of error of 3 or less with a .95 probability when the population standard deviation equals 11 is
A) 10.
B) 11.
C) 51.
D) 52.

Question

Quizplus · Accepted Answer

The formula to calculate the sample size needed is n = (z * σ / E)^2, where z is the z-score for the desired confidence level (1.96 for a .95 probability), σ is the population standard deviation, and E is the desired margin of error (3 in this case).

Plugging in the values, we get n = (1.96 * 11 / 3)^2 = 52.03. Since we can't have a decimal for a sample size, we round up to the nearest whole number and get 52. Therefore, the answer is D.

The Sample Size Needed to Provide a Margin of Error