If I’m in the store and want to know the price-per-pound of food, do I divide the weight by the dollars, or do I divide the dollars by the weight?
In: Economics
This is a simple dimensional analysis. The answer is in your question.
Unit of the price is $
The unit of weight is lb (pounds)
per is a division
So the unit of price-per-pound = $/lb This is the unit of the result just do the calculation with the units
If the cost is 10$ and the weight is 2 lb there is only one operation that results in $/lb = price per pound
10$ / 2lb = 5$/lb
the answer is in your question price-per-pound =price/pound
So ” **I divide the dollars by the weight” is correct.**
That is how all units like that work,
mpg= miles per gallon
you drove 100 miles and used 2 gallons of fuel
100miles/ 2 gallon = 50miles/gallon
Do calculation including units is a very simple way to pick up a lot of error as you tend to know the unit of the result you like and can check if that’s what you got.
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