Arithmetic Ability
 Probability

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Q.

A bag contains 4 white, 5 red and 6 blue balls. Three balls are drawn at random from the bag. The probability that all of them are red, is:

View Answer

Correct choice: A

Explanation:

Let S be the sample space. Then, n(S) = number of ways of drawing 3 balls out of 15 = 15C3 =15*14*133*2*1 = 455. Let E = event of getting all the 3 red balls. n(E) = 5C3 = 5*42*1 = 10. => P(E) = n(E)/n(S) = 10/455 = 2/91.
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