There are 15 juniors and 21 seniors in the Service Club. The club has to send four representatives to the State Conference.
(i) How many different ways are there to select a group of four students to attend the conference?
(ii) If the members of the club decide to send two juniors and two seniors, how many different groupings are possible?
(i): 36C4 , (ii): 15C2×21C2
The number of ways of selecting a group of four students to attend the conference = 36C4
The number of ways of selecting a group of four students such that the members of the club have two juniors and two seniors = 15C2×21C2