A student interested in jazz plans to buy 3 CDs. She is interested in 2 featuring piano, 3 featuring trumpet, and 4 featuring saxophone.

(a) In how many ways can the 3 CDs be selected?

(b)In how many ways can the selection be made if CDs featuring at least 2 different instruments are selected?

Question

A student interested in jazz plans to buy 3 CDs. She is interested in 2 featuring piano, 3 featuring trumpet, and 4 featuring saxophone. 

(a) In how many ways can the 3 CDs be selected? 
 
(b)In how many ways can the selection be made if CDs featuring at least 2 different instruments are selected?

zarkon · Answer

what have you tried?

anonymous · Answer

I figured out the first part.  It would be combination because we have 3 CDs selected from 9, which is C(9,3).  Order doesn't matter in this case.   So part one = 84.  Where I'm stuck is finding the compliment of 2 different instruments, which would be "all instruments the same"

akashdeepdeb · Answer

c(9,3) but then I believe you have to divide it by 4!.2!.3! [Because we have to get rid of the same genre and different music]

anonymous · Answer

managed to get correct answer. thank you