SOLUTION: 240 miles where travel in 7 hours 1st part of the trip was travel at 20 miles/hr then the speed was double for the second part , how many miles where travel at 20 mph
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Question 649364: 240 miles where travel in 7 hours 1st part of the trip was travel at 20 miles/hr then the speed was double for the second part , how many miles where travel at 20 mph Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! 240 miles were traveled in 7 hours. 1st part of the trip was traveled at
20 miles/hr, then the speed was doubled for the second part.
How many miles were traveled at 20 mph?
:
Let d = distance traveled at 20 mph
then
(240-d) = distance traveled at 40 mph
:
Write a time equation; time = dist/speed
:
20mph time + 40mph time = 7 hrs + = 7
multiply by 40 to clear the denominators, results:
2d + 240 - d = 40(7)
d = 280 - 240
d = 40 mi at 20 mph,
then
240-40 = 200 mi at 40 mph
:
:
Confirm this, find the times at each speed
40/20 = 2 hrs
200/40 = 5 hrs
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total time: 7 hrs
