SOLUTION: The UP Rowing team can row the 18-kilometer portion of the Agusan river in 3 hours downstream and 6 hours upstream, How fast is their boat and the rate of the current of the river?

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Question 1092062: The UP Rowing team can row the 18-kilometer portion of the Agusan river in 3 hours downstream and 6 hours upstream, How fast is their boat and the rate of the current of the river?
Found 2 solutions by addingup, MathTherapy:
Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
Speed = distance/time
Let s (speed) be the speed of the boat and c (current) the speed of the current
:
S(upstream) = s-c
S(downstream) = s+c
~~~~~~~~~~~~~~~~~~~~~~~~~~
Upstream data:
d = 18
t = 6
18/6 = 3km/h <---- this is the speed of the boat going upstream.
. . . . . . . . . . . . . . . . .
Downstream data:
d = 18
t = 3
18/3 = 6km/h <--- this is the speed of the boat going downstream.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Summarizing:
S(up) : s-c = 3km/h
S(dwn): s+c = 6km/h
. . . . . . . . . . . . . . . . . . . .
Let's find the speed of the current:
S(up) : s = 3+c
S(dwn): s = 6-c
3+c = 6-c
2c = 3
c = 1.5 <-- this is the speed of the current.
Substitute in the equation to find the speed of the boat in still water:
3+1.5 = 6-1.5 = 4.5 <--- this is the speed of the boat in still water.

Answer by MathTherapy(10557) About Me  (Show Source):
You can put this solution on YOUR website!

The UP Rowing team can row the 18-kilometer portion of the Agusan river in 3 hours downstream and 6 hours upstream, How fast is their boat and the rate of the current of the river?
Let speed in still water be S, and speed of current, C
We then get:

2S = 9 ------- Adding eqs (i) & (ii)
S, or speed in still water = highlight_green%28matrix%281%2C4%2C+9%2F2%2C+%22=%22%2C+4.5%2C+%22km%2Fh%22%29%29
4.5 + C = 6 ------- Substituting 4.5 for S in eq (i)
C, or speed of current: highlight_green%28matrix%281%2C4%2C+6+-+4.5%2C+%22=%22%2C+1.5%2C+%22km%2Fh%22%29%29