JEE Main & Advanced Sample Paper JEE Main - Mock Test - 15

  • question_answer
    Two integers x and y are chosen with replacement out of the set {0, 1, 2, 3, ..., 10}. Then the probability that \[|x-y|>5\] is

    A) \[\frac{81}{121}\]                     

    B)        \[\frac{30}{121}\]

    C) \[\frac{25}{121}\]                     

    D) \[\frac{20}{121}\]

    Correct Answer: B

    Solution :

    [b]: The total number of selections of two numbers x and y from the numbers 0 to 10 \[=11\times 11=121\] Now, if \[|x-y|>5\], then the possible values for (x, y) are (0, 6), (0, 7), (0, 8), (0, 9), (0 10), (1, 7), (1, 8), (1, 9), (1, 10), (2, 8), (2, 9), (2, 10), (3, 9'), (3, 10), (4, 10), (6, 0), (7, 0), (8, 0), (9, 0), (10, 0), (7, 1), (8, 1), (9, 1), (8, 2), (10, 1), (9, 2), (10, 2), (9, 3), (10,3), (10, 4) So, there are 30 pairs of values of x and) y. Hence, the required probability\[=\frac{30}{121}\].


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