 This is a video on how to calculate probabilities using the multiplication rule in my example I have a family of five children First we want to calculate the probability of having one boy and then four girls So let b equal boy Let g equal girl So the first one has to be a boy So if I'm having five children I have a boy on the first child and then the other four children have to be girls So I'm going to calculate the probabilities of each of these trials and multiply them together The probability of having a boy is one half The probability of having a girl is one half times one half times one half times one half Multiply the numerators together to get one multiply the denominators together to get 32 So you get one out of 32 that is the probability of having one boy and then four girls exactly in that order Now what's the probability of having one boy and four girls in any order? Well, that means the boy could be the first one born That means the boy could be the second one born The boy could be the third one born And if you haven't picked up on the pattern yet The boy could be the fourth one born Or the boy could be the last one or fifth one born So out of these five total outcomes Or five possibilities where there could be one boy and four girls There are five total so all of them have a probability of one over 32 of occurring So I take one over 32 and I'll multiply by five You can write five over one since you're multiplying with the fraction Five times one is five one times thirty two is thirty two So the probability of getting one boy and four girls in any order is five out of thirty two That is an example of how to calculate probabilities using the multiplication rule Thanks for watching