A bag contains 8 red and 5 white balls. 2 balls are drawn at random. What is the probability that both are white ?



A bag contains 8 red and 5 white balls. 2 balls are drawn at random. What is the probability that both are white ?

A. 5/16

B. 2/13

C. 3/26

D. 5/39

Answer : D. 5/39


Explanation:

  • n(S) = Number of methods for drawing 2 balls out of 13 = 13C2
    = (13 x 12) / 2
    = 78.
  • n(E) = No. of methods for drawing 2 balls out of 5 = 5C2
    = (5 x 4) / 2
    = 10.
  • Therefore, P(E) = n(E) / n(S)
    = 10/78
    = 5/39.

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