If 12 municipal workers can construct a drainage canal in 15 days, how many days will it take 20 workers working at the same pace to complete the same canal?
Answer and explanation
Correct answer: D. 9 days
- Step 1: Total worker-days required = 12 15 = 180 worker-days. Step 2. With 20 workers: Days = 180 / 20 = 9 days. Answer: 9 days, using the inverse proportion 12 15 = 20 d (180 / 20 = 9). Why not the others: Direct proportion gives (20 15)/12 = 25 days, which incorrectly implies more workers take longer.
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