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Two balls are drawn, from a bag containing 3 red, 4 white...

Two balls are drawn, from a bag containing 3 red, 4 white and 5 black identical balls. Find the probability that they are all of the same colour.

A.

533

B.

1366

C.

853

D.

1966

Correct answer is D

P(two same color balls)=P(2 red)+P(2 white)+P(2 black)

P(2 red)=312×211=122

P(2 white)=412×311=111

P(2 black)=512×411=533

P(2 same color balls)=122+111+533=1966