SOLUTION: the downriver trip is 36 km each way and takes 8 hours for thr trip. the upriver destination is 60 km away and take 10 hours to get there. find the speed of the boat in still water

Question 788146: the downriver trip is 36 km each way and takes 8 hours for thr trip. the upriver destination is 60 km away and take 10 hours to get there. find the speed of the boat in still water and the speed of the river
Found 2 solutions by mananth, josmiceli:
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
The total trip takes 8 hours
rate downstream = b+c where b is boat speed and c is current speed
rate upstream = b-c
downstream
36/(b+c)+36/(b-c)=8
substitute 1/(b+c) =x
1/(b-c)=y
36x+36y=8
Upstream is 60 km
60/(b-c)=10
let 1/(b-c)=y
60y=10
y=1/6
substitute y in 36x+36y=8
36x+36/6 =8
36x=2
x=1/18
1/(b-c)=1/18
.
b+c=18
b-c=6
add the equations
2b=24
b=12km/h speed of boat
plug b to get c speed of current
m.ananth@hotmail.ca

2b=

Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = speed of the river ( the current ) in km/hr
Let = the speed of the boat in still water in km/hr
= speed of boat going downstream
= speed of boat going upstream
------------------------------------
It sounds like there is a round trip of km
which means the (+) and (-) effects of the current
cancel out
Making round trip:
(1)
(1)
(1)
Going upstream:
(2)
(2)
(2)
(2)
(2)
(2)
---------------------
The speed of the boat in still water is 9 km/hr
The speed of the river is 3 km/hr

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