A study found that 82% of elementary students buy lunch at school at least once a month. How large a sample would be necessary to estimate the true proportion within four percentage points with 95% confidence

Answer 1

n = (z/2 )^2 * pq/E^2
n = (1.96)^2 *0.82*0.18/0.04^2
n = ?

Answer 2

zero is the answer