What is the probability that either event X or Y occurs?   Use the data given below to answer the following question(s). In an event X, the probability of rolling a sum of 8 on two dice is 5/36 while the probability of rolling an 11 is 2/36 . In another event Y, the probability of rolling a 2 is 1/36, the probability of rolling a 9 is 4/36 , and the probability of rolling a 4 is 3/36 .