finite MAth
posted by Bryan .
dent who wants to buy 3 CDs, but assume that there are 4 CDs featuring the piano, 6 CDs featuring the trumpet, and 7 CDs featuring the saxophone.
(1) In how many different ways can the 3 CD's be selected?
(2) In how many ways can the selection be made if CD's featuring at least 2 different instruments are selected?

1
4+6+7=17
173=14
17!/14!
=680