a 15 member committee will be selected from 18 teachers, 20 engineers, 25 economist,22 environmentalists,and 26 medical doctors. how many 15 members committee can be formed if the committee is composed of 4 teachers, 5 engineers, 3 economists, 2 medical doctors and 1 environmentalist.

Answer 1

number of committees
= C(18,4) x C(20,5) x C(25,3) x C(22,1) x C(26,2)
= 7.8 x 10^14

Why such huge numbers?
Smaller values would have shown the concept more effectively.