Question

    A and B can complete a work in 12 days and 20 days,

    respectively. They worked together for 5 days, after which A was replaced by C and the work was completed in the next 4 days. In how many days can C alone complete 80% of the work?
    A 24 Correct Answer Incorrect Answer
    B 20 Correct Answer Incorrect Answer
    C 27 Correct Answer Incorrect Answer
    D 25 Correct Answer Incorrect Answer

    Solution

    A's one day work = 12 B's one day work = 20 Total work = 60 (LCM of 12 and 20) A's efficiency = 60/12 = 5 B's efficiency = 60/20 = 3 5 days work of A and B = 8 × 5 = 40 Remaining work = 60 - 40 = 20 ATQ: 20/(3 + C) = 4 20 = 12 + 4C 4C = 8 C = 2 Therefore,  complete 80% of the work completed by C in 60/2 × 80/100 = 24 days

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