QA – Placement Quizzes | Work and Wages | Question 11

10 men working 9 hours a day can complete a work in 24 days. How much time will it take to complete the work if 15 men are employed for 6 hours a day?
(A) 18
(B) 20
(C) 24
(D) 30

Answer: (C)
Explanation: Here, we need to apply the formula M₁ D₁ H₁ E₁ / W₁ = M₂ D₂ H₂ E₂ / W₂, where
M₁ = 10 men
D₁ = 24 days
H₁ = 9 hours/day
W₁ = W₂ = Work to be done
E₁ = E₂ = Efficiency of each man
M₂ = 15 men
D₂ = Days required by 15 men
H₂ = 6 hours/day

So, we have
10 x 24 x 9 = 15 x 6 x D₂
=> D₂ = 24
Therefore, 15 men working 6 hours / day would require 24 days to complete the work.

Note : Here, 10 men working 9 hours a day is equivalent to 90 working hours by 1 man. 15 men working 6 hours / day is also equivalent to 90 working hours by 1 man. Hence, the number of days required to complete the work would not change.
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