Suppose a sample of size 400 yields p = 0.5 You'd like to construct a confidence interval with a margin of error only half as great as the one produced by this sample. What's the minimum sample size necessary to accomplish this?
A. 800
B. 2, 400
C. 1, 200
D. 400
Ε. 1,600
B. 2,400
To reduce the margin of error by half, you would need to increase the sample size by a factor of 4. So, if the initial sample size is 400, you would need a sample size of 400 x 4 = 1,600 to achieve this reduction.