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BITSAT2019MathematicsProbabilityActual

Cards are drawn one by one at random from a well shuffled pack of 52 cards until 2 aces are obtained for the first time. The probability that 18 draws are required for this is

Options

  1. A3 34
  2. B17 455
  3. C561 15925
  4. DNone of these

Correct answer

C. 561 15925

Step-by-step solution

18 draws are required for 2 aces means in the first 17 draws, there is one ace and 16 non-ace and 18 th draw 2 nd ace. Required probability = C 16 48 × C 1 4 C 17 52 × 3 35 = 561 15925

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