UNDERSTANDING MUTUALLY EXCLUSIVE EVENTS In solving probability problems, knowing when an event is mutually exclusive is very important. An event is mutually exclusive when only one outcome can happen at a time. An example of a mutually exclusive event is the tossing of a die. When the die is tossed, it can land with only one number showing. The number showing is a mutually exclusive outcome. You will often find probability problems asking you to find the probability that any set of mutually exclusive outcomes will occur. For example, what is the probability that when a die is tossed a one or three will occur? The rule for finding the probability that a set of mutually exclusive outcomes will occur is the addition rule. The addition rule states that the probability of the mutually occurring outcomes is the sum of the probabilities of each event. Example: What is the probability that a one or three will appear when a die is tossed? The probability that a one will occur when the die is tossed is one-sixth. The probability that a three will occur is also one-sixth. Addition rule: The probability that the mutually exclusive outcome of a one showing on the die or the mutually exclusive outcome of a three showing on the die is one-third. 1. The probability that a two or four will appear when a die is tossed is 2. The probability that a five or six will appear when a die is tossed is 3. The probability that a three or four or five will appear when a die is tossed is or %. 4. The probability that a two or three or four or six will appear when a die is tossed is or %. 5. The even numbers that are on the die are _, and 6. The probability that an even number will appear when a die is tossed is or %. 7. The odd numbers that are on the die are -, and 8. The probability that an odd number will appear when a die is tossed is- or %. 9. The probability that a one or two or three or four or five or six will appear when a die is tossed is or %. 10. The probability that a zero or seven will appear when a typical die is tossed is or