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 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?

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 Puzzle Resolution | Comment 3 of 11 |

By the problem the respective distance traveled  during the onward journey and the return journey are  equal. Let this distance be s miles..

Also in terms of the tenets comprising the puzzle, it takes respectively s/30 hours and s/60 hours complete the onward journey and the return journey.

Now, the total distance traversed in the course of the entire journey.

= Distance traversed during the onward journey  +   Distance traversed during the return journey

= 2s

Consequently, the required average speed during the course of the journey

= 2s/(s/30 + s/60)

= 40 mph

Edited on October 30, 2006, 8:30 am

Edited on October 30, 2006, 8:42 am

Edited on October 30, 2006, 8:43 am

Edited on October 30, 2006, 11:00 am
 Posted by K Sengupta on 2006-10-30 08:29:34

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