SOLUTION: a train travels 180 miles in an hour less time than a bus traveling the same distance. if the speed of the bus is 15 mph slower that the speed of the train, find the speed of the t
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Question 530172: a train travels 180 miles in an hour less time than a bus traveling the same distance. if the speed of the bus is 15 mph slower that the speed of the train, find the speed of the train and bus? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! a train travels 180 miles in an hour less time than a bus traveling the same distance.
if the speed of the bus is 15 mph slower that the speed of the train, find the speed of the train and bus?
:
Let s = speed of the bus
then
(s+15) = speed of the train
:
Write a time equation, time = dist/speed
:
Bus time - train time = 1 hr - = 1
;
multiply by s(s+15); results:
180(s+15) - 180s = s(s+15)
180s + 2700 - 180s = s^2 + 15s
:
a quadratic equation
s^2 + 15s - 2700 = 0
:
Factor to
(s+60)(s-45) = 0
:
the positive solution
s = 45 mph is the speed of the bus
then
45 + 15 = 60 mph is the speed of the train
:
:
Check this by finding the times of each
180/45 = 4 hrs
180/60 = 3 hrs
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differ: 1 hrs
