John Davis, a manager of a supermarket, wants to estimate the proportion of customers that will be using food stamps at his store. How large a sample is required to estimate the true proportion to within 3% with 98% confidence?

Answer 1

Formula:
n = [(z-value)(p)(q)]/E^2

z-value = 2.33 for 98% confidence
p = .5 if no value is stated
q = 1 - p
E = Maximum error

With your data:

n = [(2.33)(.5)(.5)]/.03^2

I'll let you take it from here. Round to the next whole number.

Answer 2

647.22

Answer 3

1509