SOLUTION: The road from A to B is 10km uphill followed by 20km downhill. A motorcyclist averages 36km/h uphill and 90km/h downhill. Calculate the average speed from 1. A to B 2. B to A

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: The road from A to B is 10km uphill followed by 20km downhill. A motorcyclist averages 36km/h uphill and 90km/h downhill. Calculate the average speed from 1. A to B 2. B to A      Log On

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Question 1149105: The road from A to B is 10km uphill followed by 20km downhill. A motorcyclist averages 36km/h uphill and 90km/h downhill. Calculate the average speed from
1. A to B 2. B to A
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
The road from A to B is 10km uphill followed by 20km downhill. A motorcyclist averages 36km/h uphill and 90km/h downhill.
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Assuming the up and down speeds are the same for both directions (which seems contradictory):
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Calculate the average speed from
1. A to B
Time uphill = 10/36 hours
Time downhill = 20/90 hours
Total time = 1/2 hour
Total distance = 30 km
Avg speed = 30/(1/2) = 60 km/hr
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2. B to A
Time uphill = 20/36 hours
Time downhill = 10/90 hours
Total time = 2/3 hour
Total distance = 30 km
Avg speed = 30/(2/3) = 45 km/hr
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As pointed out by the other tutor, this won't work in the real world, only in a math problem.