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    Question

    Neha is five times as efficient as Riya and three times

    as efficient as Siya. If Riya takes 20 days to finish some work, then find the time taken by Neha and Siya to do the same work together.
    A 2 days Correct Answer Incorrect Answer
    B 3 days Correct Answer Incorrect Answer
    C 4 days Correct Answer Incorrect Answer
    D 5 days Correct Answer Incorrect Answer
    E 6 days Correct Answer Incorrect Answer

    Solution

    Since, Neha is five times as efficient as Riya, she will take one-fifth the time taken by Riya to finish the work. So, time taken by Neha to do the work = 20 ÷ 5 = 4 days And, Neha is three times as efficient as Siya, so Siya will take three times the time taken by Neha. So, time taken by Siya to do the work = 3 × 4 = 12 days Let the total work be '12x' units. So, efficiency of Neha = 12x ÷ 4 = '3x' units/day And, efficiency of Siya = 12x ÷ 12 = 'x' units/day So, required time = 12x ÷ (3x + x) = 3 days Hence, option b.

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