New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    A alone can complete the work in 36 days. B’s

    efficiency is double that of A, and C’s efficiency is half of B’s efficiency. A and B start the work together, and after 6 days, C joins them. At that point, all three reduce their efficiency to 50% of their original efficiency. How many total days will it take to complete the work?
    A 15 days Correct Answer Incorrect Answer
    B 17 days Correct Answer Incorrect Answer
    C 18 days Correct Answer Incorrect Answer
    D 20 days Correct Answer Incorrect Answer
    E 22 days Correct Answer Incorrect Answer

    Solution

    A = 1/36 B = 36 * 1/2= 18 days C = 18 * 2/1 = 36 days A + B = 6/36 + 6/18 = 1/2 Remaining work = 1 – 1/2 = 1/2 They reduced the efficiency by 50%, then complete the whole work in = 1/72 + 1/36 + 1/72 = (1 + 2 + 1)/72 = 1/18 Half of the work completed with 50% of efficiency = 9 days Required time = 9 + 6 = 15 days

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