Question

If 5 men take an hour to dig a ditch, then how long should 12 men take to dig a ditch of the same type?

• A. 25 minutes
• B. 30 minutes
• C. 28 minutes
• D. 20 minutes

Answer 1

The Correct Option is A

The correct option is (A): 25 minutes
Explanation: To solve this problem, we can use the concept of man-hours.
1. Calculate the total man-hours needed to dig the ditch:
If 5 men take 1 hour to dig the ditch, the total man-hours required is:
  \[\text{Total man-hours} = 5 \text{ men} \times 1 \text{ hour} = 5 \text{ man-hours}\]
2. Calculate how long 12 men would take:
  If 12 men are working, we can find the time taken by dividing the total man-hours by the number of men:
  \[\text{Time} = \frac{\text{Total man-hours}}{\text{Number of men}} = \frac{5 \text{ man-hours}}{12 \text{ men}} \approx 0.4167 \text{ hours} \]
3. Convert hours to minutes:
  To convert hours into minutes, multiply by 60:
  \[0.4167 \text{ hours} \times 60 \text{ minutes/hour} \approx 25 \text{ minutes}\]
So, the answer is 25 minutes.