RBI Assistant Prelims 2015 Sitting 2 Paper

Total number of balls in the bag = 15
Total possible outcomes = Selection of 3 balls out of 15 balls =15C3=

15×14×13

1×2×3

=455
Total possible outcomes = Selection of 2 balls out of 8 red balls × Selection of 1 ball out of 7 green balls
=8C2×7C1=

8×7

1×2

×7=196
Required probability =

196

455

=

28

65