If 4 men and 6 boys can do a work in 8 days and 6 men and 4 boys can do the same work in 7 days, then how many days will 5 men and 4 boys take to do the same work?
If 4 men and 6 boys can do a work in 8 days and 6 men and 4 boys can do the same work in 7 days, then how many days will 5 men and 4 boys take to do the same work? Correct Answer 8
Given:
4 men and 6 boys can do a work in 8 days
6 men and 4 boys can do the same work in 7 days
Concept used:
Time = Work/Efficiency
Calculation:
Let, M = Men; B = Boys
(4M + 6B) × 8 = (6M + 4B) × 7
⇒ 32M + 48B = 42M + 28B
⇒ 42M - 32M = 48B - 28B
⇒ 10M = 20B
⇒ M/B = 2/1
So, the efficiency of one man = 2
Efficiency of one boy = 1
Total work = × 8 = 14 × 8 = 112
Efficiency of 5 men and 4 boys = (5 × 2) + (4 × 1) = 10 + 4 = 14
Required time to finish the work = 112/14 = 8 days
∴ The 5 men and 4 boys will take 8 days to do the same work
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Feb 20, 2025