It took a crew 80 min to row 3 km upstream and back again. If the rate of flow of the stream was 3km/h, what was the rowing rate of the crew?

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- Sep 22nd 2008, 02:42 PMandrewpark2speed question
It took a crew 80 min to row 3 km upstream and back again. If the rate of flow of the stream was 3km/h, what was the rowing rate of the crew?

- Sep 22nd 2008, 03:10 PMmasters
Total distance is 3 km (1.5 km each way)

Total time is 4/3 hr (80 min)

Rate of steam is 3 km/hr

rate of boat downstream = b + 3

rate of boat upstream = b - 3

$\displaystyle d = rt$

$\displaystyle t=\frac{d}{r}$

$\displaystyle \frac{1.5}{b+3} + \frac{1.5}{b-3}=\frac{4}{3}$

Does that sound reasonable?