Question

‘X’ and ‘Y’ together can complete a work in 10 days, while ‘Y’ and ‘Z’ together can complete the work in 15 days. If ‘Y’ takes 12 days to complete the work alone then find the approximate time taken by all three together to complete 57.5% of work.

A 10 days Correct Answer Incorrect Answer
B 7 days Correct Answer Incorrect Answer
C 14 days Correct Answer Incorrect Answer
D 5 days Correct Answer Incorrect Answer
E 12 days Correct Answer Incorrect Answer

Solution

Let the total work = 60 units
Efficiency of (X + Y) = 60/10 = 6 units/day
Efficiency of (Y + Z) = 60/15 = 4 units/day
Efficiency of ‘Y’ = 60/12 = 5 units/day
Efficiency of (X + Y + Z) = (6 + 4 – 5) = 5 units/day
Required time taken = (0.575 × 60)/5 = 7 days (approx)

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