<PRE><B>Question 129018</B>
Daily Double: The daily double at most racetracks consists of selecting the winning horse in both the first and second races. If the first race has seven entries and the second race has eight entries, how many daily double tickets must you purchase to guarantee a win?
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Prob(selecting both winners) = (1/7)(1/8) = 1/56
Pron(not selecting both winners) = 55/56
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Odds in favor of selecting both winners = (1/56)/(15/56) = 1:15
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Assume the number of tickets sold is A
1:15 is the same as x/15x where x is number of winners and 15x is number 
of not winners.
x +15x = A
16x = A
x = (1/16)A
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You would have to buy at least  1/16 th of all the tickets sold.
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Cheers,
Stan H.</PRE>