题库搜索>问题求解PS-13359
Machine A, operating alone at its constant rate, produces 500 feet of a particular fiber in 2 hours. Machine B, operating alone at its constant rate, produces 500 feet of the same fiber in 3 hours. Machine C, operating alone at its constant rate, produces 500 feet of the same fiber in 5 hours. How many hours will it take machines A, B, and C, operating together at their respective constant rates, to produce 1,000 feet of the fiber?
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V1=500/2，V2=500/3，V3=500/5，T=1000/(500/2+500/3+500/5)=60/31
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题目信息1m49s
平均耗时
91%
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