SOLUTION: When the speed of a train is increased by 10 mph, it can cover a 300 mile route in one hour less time. What is the original speed of the train?
Question 688467: When the speed of a train is increased by 10 mph, it can cover a 300 mile route in one hour less time. What is the original speed of the train? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! When the speed of a train is increased by 10 mph, it can cover a 300 mile route in one hour less time.
What is the original speed of the train?
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Let s = the original speed of the train
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Write a time equation, time = dist/speed
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Original time - faster time = 1 hr - = 1
Multiply by s(s+10), this clears the denominators, resulting in:
300(s+10) - 300s = s(s+10)
:
300s + 3000 - 300s = s^2 + 10s
A quadratic equation
0 = s^2 + 10s - 3000
This factors to
(s+60(s-50) = 0
the positive solution is what we want here
s = 50 mph is the original speed
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Confirm this find the time of each scenario
300/50 = 6 hrs
300/60 = 5 hrs, 1 hr less
