Difficulty: Hard
Correct Answer: 50 days
Explanation:
Introduction / Context:We are given equivalence: 50 men or 80 women in 50 days both complete the same 1 job. Compute per-man and per-woman daily rates, then evaluate work done in successive 10-day blocks as the crew shrinks.
Given Data / Assumptions:
Concept / Approach:Compute each 10-day block’s crew rate and cumulative work. Stop when cumulative work reaches 1 job.
Step-by-Step Solution:
Block 1 (days 1–10): 40m + 48w ⇒ rate = 40/2500 + 48/4000 = 0.028; work = 0.28.Block 2 (11–20): 35m + 40w ⇒ rate = 0.024; work = 0.24; cumulative = 0.52.Block 3 (21–30): 30m + 32w ⇒ rate = 0.020; work = 0.20; cumulative = 0.72.Block 4 (31–40): 25m + 24w ⇒ rate = 0.016; work = 0.16; cumulative = 0.88.Block 5 (41–50): 20m + 16w ⇒ rate = 0.012; work = 0.12; cumulative = 1.00.Total = 50 days.Verification / Alternative check:Later blocks (if continued) would overshoot; the job is exactly completed at day 50.
Why Other Options Are Wrong:45/54/62/58 days mis-sum block outputs or assume constant crews.
Common Pitfalls:Forgetting that both men and women reduce each cycle; failing to re-compute the rate per block.
Final Answer:50 days
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