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Math

by nasir » Wed Oct 14, 2009 7:08 am
A bicyclist travels uphill from town A to town B for 2 hours at an average speed of 4 miles per hour and returns along the same road at an average speed of 6 miles per hour. What is the bicyclist's average speed for the round trip, in miles per hour?

What is the solution, with little explanation
thanks
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by jgreenle » Wed Oct 14, 2009 5:36 pm
4, distance is the same for both legs, so you just average the rates
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by jgreenle » Wed Oct 14, 2009 5:41 pm
alright, that was just a joke....the real answer is 4.8 miles/hour. Total distance equals 16 miles, total time equals 3.33 hours. Rate equals distance divided by time.
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by sadullaevd » Thu Oct 15, 2009 8:52 pm
Well, i would crack this one the following way:

t1-time uphill, t2 time downhill

2S-the round trip distance(A-B-A)

averages for time: t1=S/4, t2=S/6

average speed V=2S/(t1+t2)

v=2S/(S/4+S/6)=48/10=4.8

If there's anything wrong, please correct me.

cheers
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