SOLUTION: A motorboat travels 385 mi in 7 hours going upstream. It travels 623 mi going downstream in the same amount of time. What is the rate of the boat in still water and what is the rat

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Question 288520: A motorboat travels 385 mi in 7 hours going upstream. It travels 623 mi going downstream in the same amount of time. What is the rate of the boat in still water and what is the rate of the current?
Answer by oberobic(2304) About Me  (Show Source):
You can put this solution on YOUR website!
The basic equation we have to solve is d = rt, where d=distance, r=rate of speed, and t=time.
.
s = maximum speed of the boat in calm water
c = current speed
s+c = rate of speed going down stream
s-c = rate of speed going up stream
t = 7
.
Upstream...
d = 385
t = 7
r = d/t = 55
.
Downstream...
d = 623
t = 7
r = 89
.
s + c = 89
s - c = 55
2s = 144
s = 72
.
s - c = 55
72 -c = 55
c = 17
.
s = 72
c = 17
.
Done