Question 204073: A train goes one way at a speed of x mph and y mph on the return trip. What is its average speed for the trip.
Found 2 solutions by feliz1965, RAY100:
Answer by feliz1965(151)   (Show Source):
You can put this solution on YOUR website! Here is a tip:
Average speed = distance divide by time or A = d/t.
Can you finish now?
If not, look at the link below for extra help.
http://oregonstate.edu/instruct/mth251/cq/Stage2/Lesson/speed.2.html
Answer by RAY100(1637) (Show Source):
You can put this solution on YOUR website! velocity = distance/time,,,or t=d/v
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,total time = d/x +d/y =(dy+dx)/xy = d(x+y)/xy
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total distance =2d
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velocity total = total distance / total time = 2d / {d(x+y)}/xy = 2xy/x+y
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check,,let x=50, y=60, d=100 (all arbitrary)
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vel = 2(50)(60) / (50 +60) = 6000/110=54.55 mph
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BIG NOTE, it is NOT (50 +60) /2 = 55,,,,or (x+y)/2
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avg vel = distance/time,,,,,,200 / {100/50 +100/60} = 54.55
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