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

    Question

    A can finish a task by himself in 25 days, whereas B can

    finish the same task by himself in 10 days. A begins the task but stops after 5 days, at which point B takes over and finishes the job. How many total days were required to complete the task?
    A 13 days Correct Answer Incorrect Answer
    B 18 days Correct Answer Incorrect Answer
    C 15 days Correct Answer Incorrect Answer
    D 20 days Correct Answer Incorrect Answer
    E 12 days Correct Answer Incorrect Answer

    Solution

    Let the total work = 50 units (L.C.M of 25 and 10) Efficiency of A = 50/25 = 2 units/day Efficiency of B = 50/10 = 5 units/day Amount of work done by A in 5 days = 2 × 5 = 10 units Remaining work = 50 – 10 = 40 units Time taken by B to complete the remaining work = 40/5 = 8 days Total number of days = 8 + 5 = 13 days

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