Which of the Following Is True of the Equation [N $\frac { \pi ( 1 - \pi ) } { E ^ { 2 } }$

Multiple Choice

Which of the following is true of the equation [n ? (z?/2) 2 $\frac { \pi ( 1 - \pi ) } { E ^ { 2 } }$ ] for computing the sample size required to achieve a desired confidence interval half-width for a proportion?

A) The sample size calculated will only be an approximation.
B) The standard deviation need not be calculated first in order to compute the sample size.
C) The value for ? is always set at 1.
D) The most conservative estimate for ? is 0.5.