College Finite
posted by Emily on .
A student wants to buy 3 CDs, but assume that there are 3 CDs featuring the piano, 5 CDs featuring the trumpet, and 3 CDs featuring the saxophone. In how many ways can the selection be made if CD's featuring at least 2 different instruments are selected?

So we can't have
TTT
PPP
SSS
could have
PST  C(3,1) x C(3,1) x C(5,1) = 4
PPT  C(3,2) x C(5,1) = 15
PPS  C(3,2) x C(3,1) = 9
TTP  C(5,2) x C(3,1) = 30
TTS  C(5,2) x C(3,1) = 30
SSP  C(3,2) x C(3,1) = 9
SST  C(3,2) x C(5,1) = 15
total = 108 
108 is not correct. Thanks for trying tho Reiny!

It was a simple typo,
in the first of the listings , it should have been
PST  C(3,1) x C(3,1) x C(5,1) = 45
changing my total to 153