Same job, different crew size: If 36 men can do a piece of work in 25 hours, in how many hours will 15 men do the same work (same rate)?

Introduction / Context:
Work done is men * hours for a fixed job. With fewer men, the required hours increase so that the product remains constant. We compute total man-hours and then divide by the new crew size.

Given Data / Assumptions:

• 36 men complete in 25 hours.
• New crew: 15 men.

Concept / Approach:
Total man-hours = men * hours = constant for the job. So hours2 = (36 * 25) / 15.

Step-by-Step Solution:

Verification / Alternative check:
Proportionality: reducing men by a factor of 36/15 = 2.4 increases time by 2.4; 25 * 2.4 = 60.

Why Other Options Are Wrong:

• 45, 55, 72: Do not preserve the constant 900 man-hours for completion.

Common Pitfalls:
Multiplying instead of dividing by the new crew size or mixing units. Keep the men * hours product equal to the known job total.

Final Answer: