The sample size can be calculated using the formula:
n = p (1-p) (Zc / m)^2
where:
p = proportion of students who received lunches= 0.5
Zc = taken from standard tables at 99% CI = 2.575
m = margin of error = 0.07
Substituting known values:
n = 0.5 (1-0.5) (2.575/0.07)^2
n = 338.3
n =
339 samples
