WBJEE 2012 Math Solved Paper

Total number of selections of three balls in which balls of both colours are drawn
= 2 red balls and 1 white ball + 1 red ball and 2 white balls
=8C2×5C1+8C1×5C2
=140+80=220
∴ Required probability
=‌

220

13C3

=‌

220×6

13×12×11

=‌

10

13