Helen and Patty both belong to a club of 25 members. A committee of 4 is to be selected at random from the 25 members. Find the probability that both Helen and Patty will be selected.

Guest Apr 9, 2017

We are just countng sets, here......


The total possible sets  formed from choosing 4 members from 25  is C(25,4)  = 12650


However.......we are only interested in the sets that contain both Helen and Patty......so.....we want to choose any 2 other members from the remaining 23  = C(23,2)  = 253


So....the probability that both Helen and Patty  are chosen  =  253 / 12650 =

1/50  = .02  =   2%



cool cool cool

CPhill  Apr 9, 2017

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