The standard error of the mean for a sample of 100 is 30 In

The standard error of the mean for a sample of 100 is 30. In order to cut the standard error of the mean to 15, we would

A-Increase the sample size to 200.

B- Increase the confidence level.

C- Increase the sample to size to 400

D- Decrease the sample to 50

Solution

The standard error of the mean for a sample of 100 is 30.

That is /n=30

=30*10=300

Now, if standard error of the mean is 15, then

300/n=15

N=400

C- Increase the sample to size to 400