posted by Tesa on .
You wish to learn the proportion of MBA students that are female within 3%, and with 98% confidence. How large of a sample should you get?
Try this formula:
n = [(z-value)^2 * p * q]/E^2
= [(2.33)^2 * .5 * .5]/.03^2
I'll let you finish the calculation.
Note: n = sample size needed; .5 (if no value is stated in the problem) for p and .5 (which is 1 - p) for q. E = maximum error, which is .03 (3%) in the problem. Z-value is found using a z-table (for 98%, the value is approximately 2.33). Symbols: * means to multiply and ^2 means squared.
I hope this will help get you started.