Question 266987
The odds in favor of Sprinting Sally winning the horse race are 19:2. Determine the probability that Sprinting Sally wins the horse race 
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If "odds for an event (e)" are a:b
then P(e) = a/(a+b) P(not e) = b/(a+b)
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Your problem:
P(Sally wins) = 19/(19+2) = 19/21
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Cheers,
Stan H.