Math  probability!
posted by kristen .
a club has 15 members plus their president. a 5 person committee is to be formed.
A) how many committees include the president?
B) how many committees don't include the president?
C) how many committees altogether?

a) so we need 4 more from the 15members
= C(15,4) = 1365
b) no president in selection
= C(15,5) = 3003
c) no restriction, choose 5 from the 16
= C(16,5) = 4368
notice: 1365 + 3003 = 4368