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Old Riddle

  1. Nov 8, 2006 #1
    When a bushel of wheat is worth 9 lire, the bakers make a loaf of bread weighing 6 ounces, when a bushel of wheat is worth 11 lire, how big is a loaf of bread? (the price of a loaf is constant)

    from Trevisio Arithmetic

    here is how i approached it, tell me if i'm wrong:

    let there be n ounces in a bushel. therefore 1 bushel = n/6 loaves therefore 9/(n/6) = price per loaf, and since this is constant, let it equal c. then if a bushel of wheat is equal to 11 lire, then 11/(n/x) = c where x is the weight of each loaf. therefore 11/(n/x) = 9/(n/6) and we get that x=54/11

    is this right?
    Last edited: Nov 8, 2006
  2. jcsd
  3. Nov 10, 2006 #2
    things to think about --

    If wheat is more expensive, but the loaf costs the same... will the loaf be larger/smaller?

    Then -- you don't have units on the loaf size/weight. Carrying units in your calculations will make it easier to check if you've done the math right.

    These checks will tell you that your number is probably correct... but your teacher will likely want units.
  4. Nov 10, 2006 #3


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    Science Advisor

    I thought I had responded to this yesterday but my internet link was acting up and apparently it didn't get through. You got the right answer but you reasoning doesn't look quite correct. I would do this as an "inverse proportion" problem (inverse because increasing the price of wheat will decrease the size of a loaf): 9*6= 11*x so x= 54/11.
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