We have calculated a confidence interval based on a sample of size n = 100. Now we want to get a better estimate with a margin of error that is only one-fourth as large. How large does our new sample need to be?
A) 400
B) 1600
C) 50
D) 200
E) 25

Question

Quizplus · Accepted Answer

To reduce the margin of error to one-fourth, the sample size must be increased by a factor of 16 (since the margin of error is inversely proportional to the square root of the sample size). Therefore, the new sample size should be 100 * 16 = 1600.

We Have Calculated a Confidence Interval Based on a Sample