Unformatted text preview: Math 218
Quiz 4 2/ 12/09 Show Your Work 1. Let Y be a continuous random variable with density function f}, (y) = 5y”5 for
1 S y S 00.
21) Find P(1£ Y S 2). 2 .
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l c) Find the standard deviation of Y. a: {I} TdUmfl‘A , Uni—(V) '= [SUI—{gykgclud/ ‘f‘: = $571,421? — 0.2801 ,_ n r300 ' ,1 x ‘
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2. You have a small jelly bean jar on youere—sliar work and you ﬁlled it to the top
Monday morning. On Monday, 40% of the beans were eaten. Of those that were left,
80% of them were eaten on Tuesday. Of those that were left 60% were eaten on
Wednesday, and then all the rest were eaten on Thursday (note, no new jelly beans were ever added to the jar). Let X= the number of entire days a randomly chosen jelly bean sat in your jar. (So x = 0 means that the selected jelly bean was eaten on Monday since it did
not sit in the jar for that entire day.) a) Find PX(X). (Hint drawing a probability tree may be helpﬁil.) ' l—€ MQJYﬂgb 305% M &
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b) Fiasco. ' ' "
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c) Find the standard deviation of X.
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 Spring '06
 Haskell
 Math, Probability

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