Question

There are $10$ students from whom a committee of $3$ is to be formed. Given that $2$ particular students, find the probability that either one is in the committee.

Answer 1

3 students can be selected out of 10 students ion 10C3 ways.

= (10x9x8)/(3x2x1)

=120 ways

Let 2 particular students be A,B.

Either one of them can be selected in 2C1 ways.

Ow remaining 2 students can be selected from remaining 8 students in 8C2 ways.

Thus total possibility = 2C1 x 8C2

= 2x28

= 56 ways

Thus required probability = 56/120

= 7/15