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I wanted found if is better composed yield (a x b) or sum of yields (a + b) and why.

And while on that i found one quite counterintuitive thing, namely that:

0.9 * 1.2 = 1.08

is same as

1.2 * 0.9 = 1.08

I know that this is very basic commutative law.

But if you use your experience with percentages, you know that depends on the base. It is something else to add 20% to 100 or to 120. So base number matters. But in the case above, it is same result if you add 20% to 100 and then take 90% of it, or take 90% of 100 and then add 20% to it. It is little bit counterintuitive, or is it just me?

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luky
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1 Answers1

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No, it is not counterintuitive. Basically the bigger your base is, the more you add or take a way.

So if you add 20% and then take away 10% you take away more, as the base is larger.

If instead you take away 10% and then add 20% you add less, as the base is smaller.

Lazy
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  • yes i understand that bigger base make bigger parts :). maybe one just has to accept it the way like 2 * 3 is same as 3 * 2 that there is some case of equilibrity in it regardless if it are natural numbers or floats – luky Aug 28 '21 at 21:28
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    I think you should make it clear that your (and the OP) are using the word "base" here to mean the initial value of the calculation. – Rob Arthan Aug 28 '21 at 21:28
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    No. The OP used the word "base" as the thing the percentage is applied to. So in 1001.20.9 the base for 1.2 would be 100, and the base for 0.9 would be 100*1.2. – Lazy Aug 28 '21 at 21:30
  • @Lazy: I think the OP is confused about the meaning of the word "base" in this context. So please make it clear what your interpretation is rather than just disagreeing with me on the basis of your reading of the questions. – Rob Arthan Aug 28 '21 at 21:40