SOLUTION: A bus trip of 450 km would have taken 1 hour less if the average speed for the trip had been greater by 5km per hour. What was the average speed, in km per hour, for the trip ?

Question 847278: A bus trip of 450 km would have taken 1 hour less if the average speed for the trip had been greater by 5km per hour. What was the average speed, in km per hour, for the trip ?
I hope you can help me to solve this problem. Thank you in Advance :D
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A bus trip of 450 km would have taken 1 hour less if the average speed for the trip had been greater by 5km per hour. What was the average speed, in km per hour, for the trip ?
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Original trip DATA:
dist = 450 km ; time = t hrs ; rate = d/t = 450/t kph
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New trip DATA:
dist = 450 km ; time = t-1 hrs ; rate = 450/(t-1) kph
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Equation:
New rate - original arate = 5 kph
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450/(t-1) - 450/t = 5
450t -450t+450 = 5t(t-1)
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5t^2-5t-450 = 0
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t^2 -t -90 = 0
(t-10)(t+9) = 0
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Positive solution:
t = 10 hrs. (original trip time)
450/10 = 45 kph (original rate)
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Cheers,
Stan H.
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