In this section we looked at the Binomial distribution by finding a formula for the probability of getting k successes in n independent trials. We did this by analysis of a tree diagram representing all possible results of the n trials. We then did a few simple examples where we saw that the number of girls in a family of four where the probability of having a girl is a half is binomially distributed. Next we proved the Inclusion Exclusion formul a for two events and then extended this result to n events with a proof that used mathematical induction.