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AP EAMCET202123 Aug 2021Morning ShiftMathematicsProbabilityActual

Two urns identical in appearance contain respectively 3 green and 2 black balls and 2 green and 5 black balls. One urn is selected at random and a ball is drawn from it. The probability that it is black is

Options

  1. A39 70
  2. B37 70
  3. C41 70
  4. D33 70

Correct answer

A. 39 70

Step-by-step solution

There are two urns Urn 1 contains 3 green and 2 black balls. Urn 2 contains 2 green and 5 black balls. Let A be event of selecting black ball. Probability of selecting black ball from urn 1= 2 5 Probability of selecting black ball from urn 2= 5 7 Since, one urn is selected at random hence selecting one urn have probability 1 2 . P(A)= 1 2 ( 2 5 + 5 7 )= 1 2 ( 14+25 35 )= 39 70

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