A bag contains 7 green and 8 white balls. If two balls are drawn simultaneously, the probability that both are of the same colour is -.

7/15





NA

Solution:

Given: Tota number of balls = 15

Number of ways in which two balls can be drawn from 15 balls,

= 15C2 = (15 × 14) / 2 = 105

Number of ways in which two same colour balls can be picked from 7 green balls,

= 7C2 = (7 × 6) / 2 = 21

Number of ways in which two same colour balls can be picked from 8 white balls,

= 8C2 = (8 × 7) / 2 = 28

So, Probability that the both drawn balls are of same colour

P = 7C2/15C2 + 8C2/15

P = 21/105 + 28/105

P =49/105

P = 7/15

So, the correct answer is 7/15.