Hello Terdoo,
A Bernoulli random variable X is a random variable that takes on only two values, 0 or 1. "X=1" is called "success", while "X=0" is called "failure". The probability of success (that is, P(X=1)) is usually represented as p. You are given that p = 0.4 in this problem. There is a simple formula for the variance of a Bernoulli random variable with probability of success p. It is given by Var(X) = p(1 - p). Therefore,
Var(X) = .45(1 - .45) = .2475
Let me know if you need any further help.
William
