So what is the probability that our random variable x is equal to three? Well this is going to be five. Out of the five flips, we're going to need to choose three of them to be heads to figure out which of the possibilities involve exactly three heads. And this is over 32 equally likely possibilities. And this is going to be equal to, so five choose three, is equal to five factorial over three factorial times five minus three factorial. Actually let me just write it down. Five minus three factorial, which is equal to five factorial over three factorial times two factorial.