RBI Grade B Officers 2011 feb Paper

(5) Total number of marbles in theurn = 15
P(S) = Total possible outcomes= Selection of 2 marbles at randomout of 15 marbles
=15C‌2=

15×14

1×2

=105
P(E) = Favourable outcomes= Selection of 2 marbles out of 2green marbles =2C‌2=1
∴Required probability
=

P(E)

P(S)

=

1

105