SBI PO 27 June 2015 Paper

Total number of balls
= 4 + 6 + 5 = 15
Total possible outcomes = selection of 3 balls out of 15 balls
=

15

‌

C3 =

15×14×13

1×2×3

= 455
Total favourable outcomes= selection of 2 balls out of 6 green balls and selection of 1 ball out of 5 blue balls
=

6

‌

C2×

5

‌

C2 =

6×5

1×2

× 5
= 75
∴ Required probability
=

75

455

=

15

91