SOLUTION: During a charity ride, Seal and Keith each cycle 120km. Keith's average speed is 2km faster than Seal's average speed. If Keith takes 40 minutes less time to complete the journey,
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Question 890448: During a charity ride, Seal and Keith each cycle 120km. Keith's average speed is 2km faster than Seal's average speed. If Keith takes 40 minutes less time to complete the journey, write an equation and solve to find Seal's average speed during the charity ride. Answer by lwsshak3(11628) (Show Source):
You can put this solution on YOUR website! During a charity ride, Seal and Keith each cycle 120km. Keith's average speed is 2km faster than Seal's average speed. If Keith takes 40 minutes less time to complete the journey, write an equation and solve to find Seal's average speed during the charity ride.
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let x=Seal's average speed
x+2=Keith's average speed
travel time=distance/speed
..
lcd:x(x+2)
120(x+2)-120x=2(x^2+2x)/3
120x+240-120x=(2x^2+4x)/3
240=(2x^2+4x)/3
2x^2+4x-720=0
x^2+2x-360=0
(x-18)(x+20)=0
x=-20(reject)
or
x=18
Seal's average speed=18 km/hr
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