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Disjoint Events. Points to remember…. (1.) The probability of an event happening must be between 0 and 1. (2.) If an event is guaranteed to happen, the probability of that event is 1. Example : When you flip a coin, what is the probability that you get heads or tails?.
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Points to remember… (1.) The probability of an event happening must be between 0 and 1. (2.) If an event is guaranteed to happen, the probability of that event is 1. Example: When you flip a coin, what is the probability that you get heads or tails? (3.) If an event is not possible, the probability of that event is 0. Example: When you roll one number cube, what is the probability that you roll a 7?
Disjoint Events: Events that do not share any common outcomes. Overlapping Events: Events that share one or more common outcomes. B A A B Events A and B are disjoint Events A and B are overlapping
Examples: Tell whether the events involving the spinner are disjoint or overlapping. Event P: spin an odd number Event Q: spin a prime number Event S: spin an odd number Event T: spin an even number
Tell whether the events involving the deck of cards are disjoint or overlapping. Event A: draw a red card Event B: draw a black card Event G: draw a red card Event H: Draw a king
Probability of Disjoint Events For two disjoint events, the probability that either of the events occurs is the sum of the probabilities of the events.
Examples: (1.) After rolling a number cube once, what is the probability that you roll a 2 or a 3? (2.) If you select one card from a standard deck of cards, what is the probability that you select a diamond or a heart? (3.) If you select one card from a standard deck of cards, what is the probability that you select a king or a jack?
Two disjoint events in which one or the other must occur are called complementary events. Given two complementary events A and B, Examples of complementary events. Drawing from a deck of cards a number cube Rolling a number cube Event C: Drawing a red card Event P: Rolling an even number Event Q: Rolling an odd number Event D: Drawing a black card
Sign Language At your school, 3% of the students know sign language. (a.) What is the probability that a randomly chosen student does not know sign language? (b.) There are 267 seventh graders at your school. Estimate how many do not know sign language.