A sample of size n is used to estimate the confidence interval for a proportion.Upon review,you consider the standard deviation too large.If you want to reduce your standard deviation so that it is a tenth (1/10)of the original size,what size sample do you need?
A)10n
B)100n
C)1000n
D)10,000n

Question

Quizplus · Accepted Answer

The standard deviation of a proportion is proportional to the square root of 1/n, where n is the sample size. To reduce the standard deviation to a tenth of its original size, you need to decrease the variance by a factor of 100 (since (1/10)^2 = 1/100). To achieve this, you need to increase the sample size by a factor of 100, making the correct answer 100n.

A Sample of Size N Is Used to Estimate the Confidence