Arithmetic Ability
 Probability

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Q.

Find the probability that one ball is white when two balls are drawn at random from a basket that contains 9 red, 7 white and 4 black balls.

View Answer

Correct choice: D

Explanation:

Total number of elementary events = 20C2 ways =190 There are 7 white balls out of which one white can be drawn in 7C1 ways and one ball from remaining 13 balls can be drawn in 13C1 ways. So,favourable events = 7C1*13C1 Therfore,required probability = (7C1*13C1 )/20C2=91/90
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