Twelve men can complete a job in 24 days (constant rate and identical efficiency). If only 8 men are engaged, in how many days will the job be finished?

Difficulty: Easy

Correct Answer: 36

Explanation:


Introduction:
With identical workers at a constant rate, total work (in man-days) is fixed. Changing the number of men scales time inversely. We simply compute the total man-days from the first scenario and divide by the new headcount to get the new duration.


Given Data / Assumptions:

  • 12 men complete the job in 24 days.
  • All men are assumed identical and work at a constant pace.
  • Now only 8 men will work on the same job.


Concept / Approach:
Total work W = 12 * 24 man-days. With 8 men, days needed D = W / 8. This is a direct inverse proportion of time with respect to the number of workers for fixed total work and constant efficiency.


Step-by-Step Solution:

Total work W = 12 * 24 = 288 man-days Days with 8 men: D = 288 / 8 = 36 days


Verification / Alternative check:
Compare ratios: time ∝ 1/men, so D_new = 24 * (12/8) = 24 * 1.5 = 36, consistent with the man-day calculation.


Why Other Options Are Wrong:
28, 48, 52, or 32 days do not preserve the constant man-days of 288 for 8 men.


Common Pitfalls:
Using direct proportion (time increasing with men) instead of inverse, or forgetting the job remains identical in scope.


Final Answer:
36

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