Question 113
DIRECTION for the question: Solve the following question and mark the best possible option.
David and Michael together can finish a job in 4 days 19 hrs 12 min. If David works at two-thirds Michael's speed, how long does it take Michael alone to finish the same job?
Solution
We will assume that the efficiency of Michael = 3x units per min and David's efficiency will be 2/3 * 3x = 2x units per min.
Together, their efficiency is 5x units/min and the total time taken by them to finish the job is (4*24 + 19)*60 + 12 mins = 6912 mins.
So, the total work = 6912*5x units.
Michael alone can do this job in $$\frac{6912\times\ 5x}{3x}=2304\times\ 5\min\ =192hrs\ =8\ days$$.
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