An engineer undertakes a project to build a 15 km road in 300 days and…
2025
An engineer undertakes a project to build a 15 km road in 300 days and employees 45 men for this. After 100 days he finds that only 2.5 km road has been completed. Find number of extra men he must employ to finish work in time?
- A.
43
- B.
45
- C.
55
- D.
68
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Correct answer: D
Key idea: determine the actual productivity from the work done so far and use men × days × rate = work.
Total road = 15 km. Work done so far = 2.5 km, so remaining work = 15 − 2.5 = 12.5 km. Time left = 300 − 100 = 200 days.
Observed rate per man per day = work done / (men × days) = 2.5 / (45 × 100) = 1/1800 km per man-day.
Let total men required now be N. Then N × 200 days × (1/1800 km per man-day) = 12.5 km.
Solve for N: N = 12.5 × 1800 / 200 = 112.5 men.
Extra men needed = 112.5 − 45 = 67.5, which must be rounded up to a whole person, so 68 extra men.
Answer: 68 extra men.