2. Assume I get married and have three children, and the random variable X is the number of sons (males). What is the probability, mean, and variance of having two sons (males) in this case? (Assume that having a son or daughter are equally likely).

Questions to ask and that helps you solve this problem: what is the type of the random variable, is it discrete or continuous? This will reduce the number of candidate's distributions to consider. Then, you can think which distribution best describe your problem. Afterwards, try to determine the parameters of the distribution and then apply the formula.