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posted by  jeffro_i4i on 10/10/2008 11:03:30 AM  |  status: Closed  

Combinations

Course Textbook Chapter Problem
Discrete Math N/A N/A N/A
Question Details:
Dave chooses 4 different pastries of 15 from a baker. Andrea then chooses 2 of Dave's 4. John then chooses 1 of Andreas 2. In how many ways is this possible?
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posted by Anonymous on 10/10/2008 11:27:15 AM  |  status: Live
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jeffro_i4i's comment:
"Quick response and good explanation"
Response Details:
Look at problem in reverse order: John can end up with any one of 15. This means besides the one that John ends up with Andrea had a choice of one of the other 14. Dave has two others out of the 13 that Andrea and John did not end up with. Thus the total number of possibilities is 15 * 14 * (13 choose 2) =  15 *14 * 13 *12/2 = 16380.
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