In Estimating the Standard Deviation in the Population for the Formula

Multiple Choice

In estimating the standard deviation in the population for the formula for calculating the sample size for estimating a mean,we can use some prior knowledge about the

A) sample to estimate our standard deviation.
B) population,undertake a pilot study or estimate the range,and divide by 10.
C) population,undertake a pilot study or estimate the range,and divide by 6.
D) Either of the two;b or c would work.
E) None of the above;if you do not have the actual standard deviation,you cannot use the formula.