WARM - UP The American Red Cross says that about 45% of the US Population has Type O blood, 40% Type A, 11% Type B, and the rest Type AB. a.) Selecting one individual, what is the probability that: 1. has Type AB blood? 2. has Type A or Type B? 3. is NOT Type O? b.) Among four potential donors, what is the probability that: 1. all are Type O? 2. no one is Type AB? 3. at least one person is Type B? P(AB) = 1 – P(OUAUB) = 0.04 P(AUB) = 0.51 P(OC) = 0.55 P(O∩O∩O∩O) = 0.041 P(ABC∩ABC∩ABC∩ABC) = 0.849 1 – P(BC∩BC∩BC∩BC) = 0.373

Monty Hall problem Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, which always a goat. He then says to you, "Do you switch your choice or stay?” What should you do? Does it matter?

Monty Hall problem 1/3 2/3 2/3 Do NOT Switch Switch Win = 33% Win = 66%

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Monty Hall problem Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, which always a goat. He then says to you, "Do you switch your choice or stay?” What should you do? Does it matter?

Monty Hall problem Do NOT Switch Switch Win = 33% Win = 66%

More with Multiplication Rule 4. A password for a certain computer application MUST be exactly 5 characters long. (Character = Alphabet and Digits) If the first character can not be a number, how many password combinations are possible if: a.) you are NOT allowed to Repeat any character? _____ _____ _____ _____ _____ b.) you are allowed to Repeat? 26 x 35 x 34 x 33 x 32 = 32672640 26 x 36 x 36 x 36 x 36 = 43670016