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AP EAMCET202022 Sep 2020Evening ShiftMathematicsProbabilityActual

A bag contains books numbered 1 to 20 . Three books are drawn from the bag with replacement. The probability that largest number on the book is 7 .

Options

  1. A2 17
  2. B1 20
  3. C1- ( 7 20 )^3
  4. D( 7 20 )^3- ( 6 20 )^3

Correct answer

D. ( 7 20 )^3- ( 6 20 )^3

Step-by-step solution

The total probability of selecting 3 books and whose page number is less than or equal to 7 is ( 7 20 )^3 . Total probability of selecting 3 books whose page number is less than 7 is ( 6 20 )^3 . Requiried probability = ( 7 20 )^3- ( 6 20 )^3 Hence, option (4) is correct.

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