We have calculated a confidence interval based upon a sample of n = 200. Now we want to get a better estimate with a margin of error only one fifth as large. We need a new sample with n at least
…
A) 240
B) 5000
C) 1000
D) 40
E) 450

Question

Quizplus · Accepted Answer

The margin of error is inversely proportional to the square root of the sample size (n). To reduce the margin of error by a factor of 1/5, we need to increase the sample size by a factor of (5)^2 = 25. Therefore, the new sample size should be 200 * 25 = 5000.

We Have Calculated a Confidence Interval Based Upon a Sample