perplexus.info :: Just Math : Travelling

Travelling (Posted on 2006-10-30)

You are travelling to point B from point A at a speed of 30mph. You travel back to point A from Point B (taking the same route) at 60mph. What is your average speed?

See The Solution Submitted by Paddy

Rating: 2.4000 (5 votes)

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Solution

| Comment 11 of 12 |

total distance : 2X, x being the distance between a and b

total time: x/30+x/60

average speed: distance/time=2x/(x/30+x/60)=3600x/(30x+60x)=3600/90=40 mph

Posted by Jonathan Lindgren on 2007-07-08 05:34:46

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