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Thread: Ratio

  1. #1 Ratio 
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    Hi,

    How to calculate proportions a:b:c = ? : ? : ? for following values for example:

    a = 25
    b = 15
    c = 10

    Thank you for your help.


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  3. #2  
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    Okay, there's two steps here. First you already have the ratio. Let's say my numbers are 7,000 and 3,000 and 29,000.

    So my ratio is 7,000 : 3,000 : 29,000.

    But I'm sure you're looking for the simplest ratio, and to do so this, you need to find the greatest common divisor (GCD), which the largest integer that divides into all the numbers evenly (without a remainder). I made my example easy -- my GCD is 1,000.

    So my simplest ratio is when I divide my numbers by 1,000 is -- 7:3:29.

    Your job is to find the greatest common divisor (GCD) for your numbers, and then divide all three numbers by your GCD.

    ###

    Where would we use these kinds of ratios? In recipes. It can be recipes for foods, or recipes for chemicals, or even recipes for role playing games. An easy to see ratio for foods is shown here in the second recipe, and ratio is 3:2:2:1:1:1.

    For chemicals, a well-known recipe is for black powder, which is composed of saltpeter, carbon and sulfur. Look here and find the recipe for powder in olden times in England. The composition of the powder was 66.6%, 22.3% and 11.1% by weight. The ratio is 66.6 : 22.3 : 11.1. But who wants to remember all those numbers, so when you simplify, you get almost exactly 6:2:1, which is much easier to remember. These numbers add up to 10, so to make 10 pounds of black powder, you'd mix 6 lbs of saltpeter, 2 lbs of carbon and 1 lb of sulfur. How much of each would you mix if you wanted to make 50 pounds?

    What about role playing games? Let's say the best mix of characters in a war party is 4 knights, 2 healers, 1 wizard, and 1 archer, so you're ratio is 4:2:1:1. What if you want to assemble a party of 25 characters? You know that your simplest ratio of 4:2:1:1 will produce a "unit" of 8 characters. Three units would make 24 characters, so you'd have a ratio in the war party of 12:6:3:3 plus one extra character of one of the classes.


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  4. #3  
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    I think you meant 9 lb of black powder.
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  5. #4  
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    Jrmonroe, big thanks!

    Thumbs up!

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  6. #5  
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    Quote Originally Posted by Harold14370 View Post
    I think you meant 9 lb of black powder.
    You're right, I didn't add properly (or check my work).
    Grief is the price we pay for love. (CM Parkes) Our postillion has been struck by lightning. (Unknown) War is always the choice of the chosen who will not have to fight. (Bono) The years tell much what the days never knew. (RW Emerson) Reality is not always probable, or likely. (JL Borges)
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  7. #6  
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    25:15:10 gives 5:3:2 or you may divide 25 by 5 15 by 5 and 10 by 5 and get the result.
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