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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