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Unformatted text preview: 2. Alex sets two alarm clocks each night to ensure that he does not sleep through his 12:30 p.m. class. His primary clock properly sounds its alarm on 80% of the mornings, while his secondary clock rings its bell on only 70% of mornings. Assume the clocks operate independently. a) (3) What percent of the time does Alexs twoclock strategy prevent him from oversleeping? That is, find the probability that at least one alarm would sound on a given morning. P( 1st OR 2nd ) = P( 1st ) + P( 2nd ) P( 1st AND 2nd ) = 0.80 + 0.70 0.80 0.70 = 0.94 . OR P( at least one ) = 1 P( none ) = 1 0.20 0.30 = 0.94 . b) (3) Find the probability that only one alarm would sound on a given morning. P( 1st only ) + P( 2nd only ) = 0.80 0.30 + 0.20 0.70 = 0.38 ....
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This note was uploaded on 02/15/2012 for the course STAT 400 taught by Professor Kim during the Spring '08 term at University of Illinois, Urbana Champaign.
 Spring '08
 Kim
 Statistics, Probability

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