Question

A large population consist of equal numbers of the digits 1 and 3.

Find the mean and variance of this population

Answer 1

We have here: 

P(X = 1) = P(X = 3) = 0.5

Therefore, Mean = E(X) = (1 + 3) / 2 = 2 is the required mean value here. 

E(X²) = (1² + 3²) / 2 = 5

Var(X) = E(X² ) - Mean² = 5 - 2² = 1 is the required variance here.