Normal approximation for the sample proportion (HSC SSCE Mathematics Extension 1): Quizzes

p̂ = x/n

Population proportion

n*p̂ ≥ 5

Larger n normalizes p̂

E(𝑝̂) = p̂

SD = √(p̂(1-p̂)/n)

To calculate probabilities

Distribution becomes normal

0.50

z = (p̂ - E(𝑝̂))/SD