Multiple choice

There are two bags on a table Bag A contains 8 red coloured pens and 5 yellow coloured pens. Bag B contains 5 red and 3 yellow coloured pens. If one pen is selected from the bags then find the probability that it is a red one?

  1. 119/208

  2. 213/208

  3. 137/208

  4. 129/208

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Assuming equal probability of selecting from either bag (1/2 each): P(red)=P(Bag A)×P(red|A)+P(Bag B)×P(red|B)=1/2×8/13+1/2×5/8=1/2×(64/104+65/104)=1/2×129/104=129/208. This matches option D.

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