SOLUTION: The distance between two piers on a river is 43.2 miles. It takes a motorboat, moving downriver, 2 hr 24 min to complete the journey. How much time does it take the same boat to go

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Question 1025688: The distance between two piers on a river is 43.2 miles. It takes a motorboat, moving downriver, 2 hr 24 min to complete the journey. How much time does it take the same boat to go back upstream if the current flows at 1.8 mph?
Found 3 solutions by josgarithmetic, lwsshak3, MathTherapy:
Answer by josgarithmetic(39616)   (Show Source): You can put this solution on YOUR website!
             rate            time         distance

DOWN         r+1.8                   43.2

UP           r-1.8            t            43.2


The DOWN part lets you find the unknown r, speed of the motorboat if no current. The UP part lets you find the asked time, .

Answer by lwsshak3(11628)   (Show Source): You can put this solution on YOUR website!
The distance between two piers on a river is 43.2 miles. It takes a motorboat, moving downriver, 2 hr 24 min to complete the journey. How much time does it take the same boat to go back upstream if the current flows at 1.8 mph?
2 hr 24 min=2.4 hrs
let x=speed of motorboat in still water
speed=distance/travel time=43.2/2.4=18 mi/hr(speed downstream)
x+1.8=18
x=16.2 mph(speed of motorboat in still water)
16.2-1.8=14.4 mph(speed upstream)
43.2/14.4=9 hrs
How much time does it take the same boat to go back upstream? 9 hrs

Answer by MathTherapy(10551)   (Show Source): You can put this solution on YOUR website!

The distance between two piers on a river is 43.2 miles. It takes a motorboat, moving downriver, 2 hr 24 min to complete the journey. How much time does it take the same boat to go back upstream if the current flows at 1.8 mph?
Time to go back upstream:  

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