SOLUTION: On a 130 mile trip, a car traveled at an average speed of 55 mph and then reduced its speed to 40 mph for the remainder of the trip. The trip took a total of 2.5 hours. For how lon

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Question 58492: On a 130 mile trip, a car traveled at an average speed of 55 mph and then reduced its speed to 40 mph for the remainder of the trip. The trip took a total of 2.5 hours. For how long did the car travel at 40 mph?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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On a 130 mile trip, a car traveled at an average speed of 55 mph and then reduced its speed to 40 mph for the remainder of the trip. The trip took 2.5 hours
:
Let t = no. of hrs at 55 mph
(2.5-t) = no of hrs at 40 mph
:
Dist = speed * time
:
Dist at 55 mph = 55t
Dist at 40 mph = 40(2.5-t)
These two distances = 130 mph
:
55t + 40(2.5-t) = 130
55t + 100 - 40t = 130
55t - 40t = 130 - 100
15t = 30
t = 30/2
t = 2 hrs at 55 mph
:
Then 2.5 - 2 = .5 hrs at 40 mph
:
Dist at 40 mph = .5*40 = 20 miles
:
:
Check using distance:
55(2) + .5(40) =
110 + 20 = 130 miles