A paddleboat can travel 60 miles upstream in the same time it takes to travel 140 miles downstream. If the current of the river is 10 mph, what is the speed of the paddleboat in still water?

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Answer 1 · 2016-04-16T15:04:54

This is a a problem that will use the formula #S = d/t#, where s is speed, d is distance and t is time.

Since the time is equal, let's solve in the formula for t.

#t = d/S#

The speed of the boat in m/ph,bgoing upstream, will be x - 10. Conversely the speed of the boat going downstream will be x + 10.

#60/(x - 10) = 140/(x + 10#

#60(x + 10) = 140(x - 10)#

#60x + 600 = 140x - 1400#

#-80x = -2000#

#x = 25#

The speed of the paddle boat in still water is 25 m/ph.