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Friday, October 17, 2008

A fun little limit problem

You drive the first half of a car trip at 30 mph. How fast would you have to travel during the second half of your trip so that the average speed of the entire trip was 60 mph?


  1. Impossible! To make the average 60mph, you'd have to go a total of twice the original distance in the same amount of time, and since we are presumably limited to the real world and no teleporters, it can't be done.

  2. This comment has been removed by the author.

  3. NEI

    (compare at TMI)

    By half, do you mean of the distance, or of the time?

    If you meant "of the distance" then I'm with i.k.

    But, half the time? Half hour at 30, half hour at 90, and we have, in total an hour passed, and 15 + 45 = 60 miles covered.

    hmmph - I had to relink


  4. ha! You guys nailed it, in two comments. I had to resort to algebra to prove it was impossible, nice summary. I meant "distance", but considering I might have meant "time" is interesting.


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