# Homework Help: Bernoulli random variable problem

1. Apr 3, 2010

### scottstapp

1. The problem statement, all variables and given/known data

Suppose we want to estimate a binomial proportion, p. We take a sample of size n and count X successes.

Consider a Bernoulli random variable, Y that is 1 with probability p and 0 otherwise. Show that the mean and variance of Y are p and p(1-p), respectively.

2. Relevant equations

3. The attempt at a solution
Not too sure what to do here. I know that the mean is calculated by $$\Sigma$$xf(x) and variance is E(X-mean)2

2. Apr 3, 2010

### rock.freak667

Well write out your sample space

y 0 1
P(Y=y)