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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 two-clock 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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