Question

A contractor undertakes to build a wall in 50 days. He employs 50 people for the same. However, after 25 days he finds that only 40% of the work is complete. How many more men need to be employed to complete the work in time?

• A. 25
• B. 30
• C. 35
• D. 20

Answer 1

The Correct Option is A

Step 1: Convert the plan to man–days.
Planned effort $\Rightarrow 50 \text{ men} \times 50 \text{ days} = 2500$ man–days (planned).
Actual effort spent in 25 days $\Rightarrow 50 \times 25 = 1250$ man–days, which equals $40\%$ of total work.

Step 2: Infer the true total work.
If $1250$ man–days $= 40\%$, then total work
$\Rightarrow \dfrac{1250}{0.40} = 3125$ man–days.

Step 3: Find remaining work and workforce needed.
Remaining work $= 60\%$ of $3125 \Rightarrow 0.60 \times 3125 = 1875$ man–days.
Days left $= 50 - 25 = 25$ days.
Required men now $\Rightarrow \dfrac{1875}{25} = 75$ men.

Step 4: Extra men to employ.
Currently there are $50$ men $\Rightarrow$ additional needed $= 75 - 50 = 25$.

\[\boxed{25}\]