Question 264464
A group of 3 students is to be selected from a group of 12 students to take part in a class in cell biology.

A) three students out of 12 can be selected in 12C3 ways = 12!/(3!*9!)

                             = 12*11*10*9!/3*2*1*9!

                             =12*11*10/3*2*1

                             =220 ways

B) no. of ways to chose the group who will not take part will be 12C9

which will be obviously equal to 12C3 = 220 ways