SOLUTION: Jane took 15 min to drive her boat upstream to​ water-ski at her favorite spot. Coming back later in the​ day, at the same boat​ speed, took her 5 min. If

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Question 1093796: Jane took
15 min to drive her boat upstream to​ water-ski at her favorite spot. Coming back later in the​ day, at the same boat​ speed, took her
5 min. If the current in that part of the river is
2 km per​ hr, what was her boat speed in still​ water?
Found 4 solutions by josgarithmetic, josmiceli, MathTherapy, greenestamps:
Answer by josgarithmetic(39620)   (Show Source): You can put this solution on YOUR website!
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Jane took
15 min to drive her boat upstream to​ water-ski at her favorite spot. Coming back later in the​ day, at the same boat​ speed, took her
5 min. If the current in that part of the river is
2 km per​ hr, what was her boat speed in still​ water?
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15 minutes is hour.
5 minutes is hour.
r, boat speed in still water.
Distance each way is the same , both directions.




Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!
= the speed of the current in km/hr
Let = the speed of the boat in still water
= the speed of the boat going downstream
= the speed of the boat going upstream
Let = one-way distance she travels
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Convert minutes to hrs
going upstream:
(1)
going downstream:
(2)
------------------------------
Set (1) = (2)

Multiply both sides by




The speed of the boat in still water is 4 km/hr
--------------------------
check answer:
(1)
(1) km
and
(2)
(2)
(2) km
OK
Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!
Jane took
15 min to drive her boat upstream to​ water-ski at her favorite spot. Coming back later in the​ day, at the same boat​ speed, took her
5 min. If the current in that part of the river is
2 km per​ hr, what was her boat speed in still​ water?
FYI: Speed in still water IS NOT , as one person claims. 

The correct speed is:  

Answer by greenestamps(13200)   (Show Source): You can put this solution on YOUR website!
 
So many different ways to solve the same problem....!


Here is what I would do.


The trip took 3 times as long going upstream as downstream.  That means her downstream speed must be 3 times her upstream speed.


If b is the speed of her boat in still water, then her upstream speed is b-2 and her downstream speed is b+2.  So








 

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