Look at this tree diagram example: P ( x 2x ) an C x P x gu -2 A fair die is rolled three times. Let S be the event that a six is obtained uppermost, and let X be the number of sixes obtained in total. Complete the tree diagram, and hence find the We will do this together in class, probability that X is 0, 1,2 and 3. Compare this with but have a go yourself first! your answers using the binomial probability formula. Pr( X = 0) = FC. Pr(X = 1) = Pr( X = 2) = in 1 st 2nd 3ra Pr( X = 3) = 1