Question

If 20 men can build a wall 66 meters long in 6 days, what length of a similar can be built by 86 men in 8 days?

• A. 49m
• B. 59m
• C. 61m
• D. 70m

Answer 1

The Correct Option is A

Wall Construction Calculation

Step 1: Work Done Formula 

The formula for work is: \[ \text{Work} = (\text{Men}) \times (\text{Days}) \times (\text{Efficiency}) \]

Given Data:

• 20 men can build a 66-meter wall in 6 days.
• We need to find the length of a similar wall built by 86 men in 8 days.

Step 2: Find the Total Work Done in Terms of Man-Days

Total work done in the first case: \[ \text{Work} = 20 \times 6 = 120 \text{ man-days to build 66 meters} \]

Step 3: Find Work Per Unit Length

Work per meter: \[ \frac{120}{66} = \frac{20}{11} \text{ man-days per meter} \]

Step 4: Compute Work Done by 86 Men in 8 Days

Total work available: \[ 86 \times 8 = 688 \text{ man-days} \]

Step 5: Find the Length of the Wall Built

\[ \text{Length} = \frac{688}{\frac{20}{11}} \] \[ = 688 \times \frac{11}{20} \] \[ = \frac{688 \times 11}{20} \] \[ = \frac{7568}{20} = 49 \text{ meters} \]

Final Answer:

The correct answer is (A) 49 meters.