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Ahhh! simple conversion!

  1. Aug 31, 2006 #1
    For some reason I'm having trouble doing a simple conversion problem:

    A person on a diet loses 6 pound(s) every 30 days. What is the loss rate in milligrams per second?

    I get 62.9989, but apparently that answer is wrong, but I'm not sure why. I may have to put it in scientific notation, but I'm not sure what I'm overlooking. Any help would be greatly appreciated.
  2. jcsd
  3. Sep 1, 2006 #2


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    1 pound = x kg
    1 kg = y mg
    -> 1 pound = xy mg

    1 day = p hours
    1 hour = q seconds
    -> 1 day = pq seconds

    pound/day : mg/s
    -> 1/1 : xy/pq

    you don't have 1 pound/day but 6/30. Each 1 pound per day is worth xy/pq mg/s, and you have 6/30 of them.
  4. Sep 1, 2006 #3


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    There are 60 seconds in a minute, 60 minutes in an hour, so 60*60= 3600 seconds in an hour. There are 24 hours in a do so (24)(3600)= 86400 seconds in a day and so 30(86400)= 2592000 seconds in 30 days.

    "pounds to milligrams" is a little harder since they are in differents systems so there are not an integer number of grams in a pound. According to http://www.onlineconversion.com/weight_common.htm, there are 453.2923 grams in a pound and so 453292 milligrams in a pound. 6 pounds in 30 days is 6(453291 milligrams)/ 2592000 seconds which is very nearly 1 milligram per second.
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