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Discussion :: Probability

  1.  The last 5 alphabets are written at random then the probability that the letters y and z are written down side by side is : -

  2. A.

    1/5

    B.

    2/5

    C.

    3/5

    D.

    4/5

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    Answer : Option B

    Explanation :

    The 5 letters can be written in 5! ways.
    Then n(S) = 5!Let E be the event that the letters y and z are written down side by side.
    (i.e., y and z are always come together).
    Now the alphabets v, w, x and (yz) can be written in 4! ways.
    And y, z written in 2 different ways.
    Then, n(E) = 4! x 2!
    Therefore p(E) = 4! x 2!/5! = 2/5.
    Hence the answer is 2/5. 


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