UPSC NDA Math Model Paper 8

A bag contain 5 black and 3 white balls,There is a

3

8

chance that a white marble will be chosen. The marble is chosen and not replaced. There are now 2 white marbles in a bag of 7 marbles, so there is now a

2

7

chance that a white marble will be chosen.
Now, P( both the balls are white) =

3

8

×

2

7

=

3

28

Hence, option (3) is correct.