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Discussion :: Probability

  1. A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random. What is the probability that none of the balls drawn is blue?

  2. A.

    \(\frac { 10 } { 2 1}\)

    B.

    \( \frac { 11 } { 2 1} \)

    C.

    \( \frac { 2} { 7 } \)

    D.

    \( \frac { 5} { 7 } \)

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    Answer : Option A

    Explanation :

    Total number of balls = (2 + 3 + 2) = 7.

     

    Let S be the sample space.

     

    Then,= Number of ways of drawing 2 balls out of 7

         

             = 7c2

       

              =\(\frac { (7*6) } { (2 *1)} \)

     

              = 21

    Let E = Event of drawing 2 balls, none of which is blue.

     n(E)Number of ways of drawing 2 balls out of (2 + 3) balls

     

              =5C2

     

             =  \(\frac { (5*4) } { (2 *1)} \)

     

             =10

     

     P (E) =\(\frac { n (E)} {n(s)}\)\(\frac { 10 } { 2 1}\)

     


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