The standard error of the mean for a sample of 100 is 30.To cut the standard error of the mean to 15,we would
A)increase the sample size to 200.
B)increase the sample size to 400.
C)decrease the sample size to 50.
D)decrease the sample to 25.

Question

Quizplus · Accepted Answer

The standard error of the mean is inversely proportional to the square root of the sample size. To cut the standard error of the mean in half, we need to increase the sample size by a factor of 4 (because sqrt(4) = 2). Therefore, we need to increase the sample size from 100 to 400 to achieve a standard error of 15. So the correct choice is B.

The Standard Error of the Mean for a Sample of 100