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    Question

    What is the probability that a number selected from

    1,2,3.......................68,69,70, is perfect square or a perfect cube?
    A 1/5 Correct Answer Incorrect Answer
    B 1/10 Correct Answer Incorrect Answer
    C 1/70 Correct Answer Incorrect Answer
    D 1/7 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    perfect squares = 1,4,9, 16,...64 = 8 numbers perfect cubes = 1,8,27,64 = 4 numbers Favourable outcomes = 1, 4, 8, 9, 16, 25, 27, 36, 49, 64 = ( 8+ 4 -2 common) Hence No. of favourable outcomes = 10 No. of total outcomes = 70 ∴ Required probability = 10/70 = 1/7

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