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?
人气：463 ℃ 时间：2020-05-07 07:35:48
解答
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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