<PRE><B>Question 717749</B>
One professor grades homework by randomly choosing 3 out of 15 homework problems to grade How many different groups of 3 problems can be chosen from the 15 problems?
Probability extension: Jerry did only 3 problems of one assignment. What is the probability that the problems he did comprised the group that was selected to be graded?
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# of ways to succeed: 1
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# of sets of 3 questions: 15C3 = 455
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P(his 3 are selected) = 1/455
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Cheers,
Stan H.
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