The excursion boat on the river takes 2.5h; hours to make th

问题描述:

The excursion boat on the river takes 2.5h; hours to make the trip to a point 12 miles upstream and to return.If the rate at which the boat travels in still water is 5 times the rate of the river current,what is the rate of the current?
1个回答 分类:英语 2014-09-26

问题解答:

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设 the rate of the current is v,则 the rate of the boat travels is 5v,
有12/(4v)+12/(6v)=2.5,v=2
 
 
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