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Unformatted text preview: STAT/MA 416 September 28, 2011 Problem Set 16: By Request (from our dinner guests), a special Harry Potter homework Name: 1. Quidditch Training. Hermione is frustrated because she is extremely good at spells but she is struggling to learn how to fly on her broomstick. She repeatedly tries to fly on the broomstick. Assume that her trials are independent, and a trial succeeds with probability . 15. She conducts trials until her 4th success, and then she stops. Let X denote the number of trials that are required until (and including) her 4th success with the broomstick. (a.) What is the mass of X ? (b.) What is the probability that it takes Hermione exactly 12 trials until her 4th success? (c.) What is the expected number of trials until Hermione’s 4th success? 1 2. Horcruxes. Harry Potter needs to find 7 Horcruxes to defeat You-Know-Who. Harry makes repeated attempts to guess which objects are Horcruxes. Assume that his guesses about Horcruxes are independent. Each time he guesses about a Horcrux, he is correct only 1 / 3 of the time. Let X be the total number of times that he makes guesses until he finds all 7 Horcruxes....
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- Fall '08
- Probability, Probability theory, Professor Trelawney