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Two balls are selected at random one by one without replacement from a bag containing 4 white and 6 black balls. If the probability that the first selected ball is black, given that the second selected ball is also black, is m n , where gcd (m, n)=1 , then m+n is equal to :

Options

  1. A4
  2. B14
  3. C13
  4. D11

Correct answer

B. 14

Step-by-step solution

Bag contains 4 white and 6 black balls A : first ball selected is black B : Second ball is also black aligned & P ( A B )= 6 10 5 9 4 10 6 9 + 6 10 5 9 = 30 24+30 & = 30 54 = 5 9 & m+n=5+9=14 aligned

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