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AP EAMCET201824 Apr 2018Morning ShiftMathematicsProbabilityActual

Two balls are drawn from an urn containing 7 white, 6 red and 8 black balls one after the other without replacement. Then the probability that atleast one of them is white, is

Options

  1. A4 9
  2. B13 30
  3. C11 30
  4. D17 30

Correct answer

D. 17 30

Step-by-step solution

Given that urn contain 7 white, 6 red, 8 black balls. Two balls are drawn one after the other without replacement, then following condition are there to get at least one of them is white (a) First White, second non-white So, required probability = 7 21 14 20 (b) First non-white, second white So, required probability = 14 21 7 20 (c) Both are white = 7 21 6 20 Required probability is = 7 21 14 20 + 14 21 7 20 + 7 21 6 20 = 17 30 .

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