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A boat moves at a rate pf 12 mph in still water. If the river's current flows at a rate of 5 mph, how long does it take the boat to travel 31 miles upstream?

 Oct 8, 2018
 #1
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Use exactly the same reasoning as in the answer to your question after this one. Make sure you change the numbers!. If you don't make any mistakes, you should get 4 3/7 hours, or about 4 hours and 26 minutes. 

 Oct 8, 2018
 #2
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Since 5 mph current is flowing AGAINST your 12 mph speed, your NET speed is   12-5 = 7 MPH

 

31 miles / 7 mi/hr = 4.4286 hr = 4 hr 25.71 min

 Oct 8, 2018

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