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Impeded by the current, the outing club took 4 hrs and 24 mins to paddle 11 km up the exeter river to their campsite last weekend. the next day, the current was with them, and it took only 2 hrs to make the return trip to campus. everyone paddled with the same intensity on both days. at what rate would the paddlers have traveled if there had been no current? what was the speed of the current?

 Jul 10, 2021
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distance / rate = time

upriver    11 / (r-c)  = 4.4 hr         r = speed if paddling in still water         c = current speed

             re-arrange to     c = (11-2r)/2

 

 

    downriver  11/ (r+c) = 2     sub in the red equation then sovle for r

                    r = 4 km/hr     

 

Use this result in either of the upstream or downstream equations to find c = 1.5 km/hr

 

 

If no current    :   11 km / 4 km/hr = 2.75 hrs       2 hrs 45 min

 Jul 10, 2021

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