SOLUTION: A boat travelling upstream goes 84 kilometers in 7 hours. If the return trip takes only 3 hours, what is the speed (in kilometers per hour) of the boat in still water?

Question 1155687: A boat travelling upstream goes 84 kilometers in 7 hours. If the return trip takes only 3 hours, what is the speed (in kilometers per hour) of the boat in still water?

Found 2 solutions by Boreal, Alan3354:
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
current is c
speed is s
distance=s*time
it goes upstream (s-c)=12 km/h
it goes downstream (s+c)=28 km/h (84/3)
therefore,
s-c=12
s+c=28
2s=40
s=20 km/h ANSWER
c=8 km/h

Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
A boat travelling upstream goes 84 kilometers in 7 hours. If the return trip takes only 3 hours, what is the speed (in kilometers per hour) of the boat in still water?
--------------
Find the 2 speeds, upstream and downstream.
The boat's speed is the average of the 2.
-----
The speed of the current is the difference between boat speed and either speed, up or down stream.

RELATED QUESTIONS
A boat travelling upstream goes 140 kilometers in 7 hours. If the return trip takes 5... (answered by ikleyn)
a boat travelling upstream goes 120 miles in 6 hours. If the return trip takes 4 hours... (answered by anand429)
Any help on this question would be greatly appreciated. The assignment is due on April 9, (answered by josgarithmetic,ikleyn)
If a boat is travelling at x mph for 3 hours upstream on a trip, and goes 2 mph faster on (answered by stanbon)
A motorboat takes 4 hours to travel 128 kilometers going upstream. The return trip takes... (answered by MathLover1,ikleyn)
A motor boat takes 5 hours to travel 200km going upstream. The return trip takes 4 hours... (answered by Boreal,josgarithmetic)
A boat takes 3 hours to travel 108 km upstream the return trip downstream takes 2 hours.... (answered by TimothyLamb)
A tugboat goes 140 miles upstream in 10 hours. The return trip downstream takes 5 hours.... (answered by richwmiller,ewatrrr)
A boat travels 105 km downstream in 5 hours. The return trip upstream takes 7 hours. Find (answered by ewatrrr)