Question 754526
A young shinobi can row 2 miles against the current in his native river in 15 minutes. He can row 2 miles with the current in 10 minutes. How fast is the current moving?
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let c=speed of current
let x=speed of canoe in still water
(x+c)=speed of canoe downstream
(x-c)=speed of canoe upstream
travel time=distance/speed
..
2/(x-c)=15/60=1/4
2/(x+c)=10/60=1/6
..
x-c=8
x+c=12
subtract:
-2c=-4
c=2
speed of current=2 mph