SOLUTION: A motorboat takes 4 hours to travel 192 km going upstream. The return trip takes 3 hours going down stream. What is the rate of the boat in still water and what is the rate of the

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Question 818452: A motorboat takes 4 hours to travel 192 km going upstream. The return trip takes 3 hours going down stream. What is the rate of the boat in still water and what is the rate of the current?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
boat speed =x km/h
current speed =y km/h
against current 4 hours
with current 3 hours

Distance against 192 miles distance with 192 miles
t=d/r against current -
192.00 / ( x - y )= 4.00
4.00 ( x - y ) = 3.00
4.00 x - 4.00 y = 192.00 ....................1

192.00 / ( x + y )= 3.00
3.00 ( x + y ) = 192.00
3.00 x + 3.00 y = 192.00 ...............2
Multiply (1) by 3.00
Multiply (2) by 4.00
we get
12.00 x + -12.00 y = 576.00
12.00 x + 12.00 y = 768.00
24.00 x = 1344.00
/ 24.00
x = 56.00 mph

plug value of x in (1) y
4.00 x -4.00 y = 192.00
224.00 -4.00 -224.00 = 192.00
-4.00 y = 192.00
-4.00 y = -32.00 km/h
y = 8.00
boat speed 56.00 km/h
current speed 8.00 km/h

m.ananth@hotmail.ca