One million couples are asked how many children they have

Question

1. Devise a method for computing the sample variance based on the frequencies, fx.

2. One million couples are asked how many children they have. Suppose the relative frequencies are f₀/n = .10, f₁/n = .20, f₂/n = .25, f₃/n = .29, f₄/n = .12, and f₅/n = .04.