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Date: Tue, 23 Oct 2012 08:52:49 +0200
From: Polytropon <freebsd@edvax.de>
To: Olivier Nicole <olivier.nicole@cs.ait.ac.th>
Subject: Re: way way off topic
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Cc: Gary Kline <kline@thought.org>,
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On Tue, 23 Oct 2012 11:31:18 +0700, Olivier Nicole wrote:
> Gary,
> 
> On Tue, Oct 23, 2012 at 11:20 AM, Gary Kline <kline@thought.org> wrote:
> >
> > apologies up front for this math type quandary. I had it in a std C program,
> > but 3+ hours of grepping havent found it.  I would have bet my last cent that I
> > had a summary Somewhere, but cant find that either.
> >
> > here is the problem as best I can remember it.
> >
> >
> >         let's say that john is 8 and his older friend, jim, is 22.
> >         how much older is exact percentage terms is jim?
> 
> That should be 22/8=2.75
> Jim is 275% older than John

Jim is 175% _older_. Why? Because 100% older means 16 years,
as 100% refers to 8 years (8+8=16, 200% older is 8+8+8=24).
Percentage is always a reference to something else, in this
question, Jim's age in relation to John's. The word "older"
means "adding percentage", refering to the base value of 8,
"divided in 100 parts" (floating point considerations aside),
to finally reach the value 22.

If the question would be different, say, "What's the percentage
of John's age regarding Jim's age?" In that case, it would be
8/22=0.3636 being 36%. Obvious: John's age is approximately
1/3 of Jim's age.

The easiest way for creating the proper calculation is to refer
to the equation

	                   percentage * 100
	percentage value = ----------------
	                     base value

and resolve it to whatever is required.

-- 
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...