SOLUTION: You paddle 12 miles downstream, with a 2 mph current, in one hour less than you can paddle 10 miles upstream against the current. What would their average speed be when there is no

Question 921946: You paddle 12 miles downstream, with a 2 mph current, in one hour less than you can paddle 10 miles upstream against the current. What would their average speed be when there is no current?
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
You paddle 12 miles downstream, with a 2 mph current, in one hour less than you can paddle 10 miles upstream against the current. What would their average speed be when there is no current?
***
let x=ave speed when there is no current(still water)
x+2=speed downstream
x-2=speed upstream
travel time=distance/speed
..
10/(x-2)-12/(x+2)=1
lcd:(x+2)(x-2)
10(x+2)-12(x-2)=(x+2)(x-2)
10x+20-12x+24=x^2-4
x^2+2x-48=0
(x+8)(x-6)=0
take positive root
x=6
ave speed when there is no current=6 mph
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