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5/17 Bell Ringer

5/17 Bell Ringer. You draw one marble from a bag: What’s the probability you select a blue marble? What’s the probability you select a yellow marble? What’s the probability you select a blue or yellow marble? What’s the probability you select a blue and yellow marble?.

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5/17 Bell Ringer

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  1. 5/17 Bell Ringer You draw one marble from a bag: What’s the probability you select a blue marble? What’s the probability you select a yellow marble? What’s the probability you select a blue or yellow marble? What’s the probability you select a blue and yellow marble? Homework: Finish today’s Independent Practice

  2. 5/17 News and Notes: • Perfection: 8th Period • Quiz Friday • Missing Quizzes – Today after school: • 2nd: Jahmeelah, Edna, Jairo • 4th: Janet, Monica, Shacora, Jasmine

  3. Quick Definition • Mutually Exclusive: Two events that cannot both happen. • Ex: A coin cannot be heads and tails, a ball cannot be blue and yellow.

  4. Example 1 • Melissa has been keeping track of the following two events: She gets a pop quiz in science class with probability 0.12, and she has to dress for PE with probability 0.5. P(A) = Prob. Of pop quiz = 0.12 P(B) = Prob of dressing in PE = 0.5 Are they M.E.? – NO!

  5. Answer the following questions • What’s the probability that Melissa has a quiz AND has to dress? • P(A ∩ B) = P(A)*P(B) = 0.12 * 0.5 = 0.06

  6. What’s the probability that she has a quiz OR has to dress? • P(A U B) = P(A) + P(B) – P(A ∩ B) = 0.12 + 0.5 – 0.06 = 0.56

  7. Example 2 • 8 cards (2 heart, 2 spade, 2 club, 2 diamond) are laid out on a desk. What’s the probability of drawing a heart or a spade? • P(A) = Prob. Of drawing a heart • P(B) = Prob. Of drawing a spade • Are they M.E.? YES!

  8. P(Heart) = 2/8 = 0.25 • P(Spade) = 2/8 = 0.25 • P(Hrt U Sp) = P(H) + P(S) – P(H ∩ S) = 0.25 + 0.25 – 0 = 0.50

  9. What’d you notice? • P(A U B) = P(A) + P(B) – P(A ∩ B) if not M.E. • But if M.E. P (A∩ B) = 0 • So, P(A U B) = P(A) + P(B) if M.E

  10. Guided Practice • Mr. Chrischilles decided to do his wedding reception at an outdoor Vineyard in Iowa next July. This raised a couple of concerns for his fiancée. She was worried that it might rain, and that it might be too hot (over 80°). To minimize her concerns, Mr. Chrischilles decided to do some key calculations.

  11. Questions on your card. • The probability that it rains on a given day in July is 0.15 and the probability that it is over 80° is 0.05. Answer the following questions on your card. • 1. Are the rain and heat mutually exclusive? • 2. What’s the probability that it will be too hot and rain during the reception? FLIP YOUR CARD • 3. What’s the probability that it will be too hot OR rain? • 4. What’s the probability that the weather will be just fine (no rain or not too hot)?

  12. Independent Practice

  13. Exit Ticket • A classroom has 10 freshmen, 10 sophomores, 15 juniors and 15 seniors. What’s the probability that a randomly selected student is a sophomore or junior? • 0.45 • 0.5 • 0.25 • 0.20

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