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    Question

    Bittu can finish a task by

    himself in 60 days, while Anoop and Bittu working together can complete the same task in 28 days. If Anoop starts the task alone and works for 35 days before stopping, how many additional days would Bittu need to complete the remaining work on his own?
    A 20 days Correct Answer Incorrect Answer
    B 18 days Correct Answer Incorrect Answer
    C 12 days Correct Answer Incorrect Answer
    D 15 days Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let the total task = L.C.M of 60 and 28 = 420 units Then, efficiency of ‘Bittu’ alone = 420 ÷ 60 = 7 units/day Combined efficiency of ‘Anoop’ and ‘Bittu’ = 420 ÷ 28 = 15 units/day So, efficiency of ‘Anoop’ alone = 15 – 7 = 8 units/day task done by ‘Anoop’ alone in 35 days = 8 × 35 = 280 units Remaining task  = 420 – 280 = 140 units So, time taken by ‘Bittu’ alone to complete the remaining task = 140 ÷ 7 = 20 days. 

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