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Christopher
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Member Rara Avis
since 1999-08-02
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Purgatorial Incarceration

0 posted 2005-01-20 12:19 PM



If anyone wants to give it a shot - I've been working on this one for a couple days now and am wholly lost. *shrug*


Here is my known equation as I have it set up right now (this part works):

B = TC (Listed separate from TC because B will be changing in a moment, which is where my problem is)

TC = (SC+STC+C) + ((SC+STC+C) x H%)

Known variables are B, TC, SC, STC, & H%

When TC does not = B, I need to solve for the adjustment of C in order to make TC = B
The part I'm having such difficulty with is that H% is a percentage, which means whenever SC, STC, and/or C changes, the value of ((SC+STC+C) x H%) is adjusted by a different amount every time.
The closest I've been able to come (and I don't even know if I'm even on the right track) is as follows:

((H%/B)*(B-TC)*100)+(B-TC)+C

Honestly, I've tried dozens of approaches & have come close a couple of times, but cannot seem to solve it.

© Copyright 2005 C.G. Ward - All Rights Reserved
Christopher
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Member Rara Avis
since 1999-08-02
Posts 8296
Purgatorial Incarceration
1 posted 2005-01-20 12:32 PM


here's an Excel spreadsheet as an example for the base equation.
http://egowhores.com/temp/Sample.xls

Ron
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since 1999-05-19
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2 posted 2005-01-20 07:42 PM


The only trick, Chris, is that you first to have rearrange the equation so that you are solving for C.

TC = (SC+STC+C) + ((SC+STC+C) * H)
TC-SC-STC = C + ((SC+STC+C) * H)
(TC-SC-STC)/H = (C/H) + SC + STC+ C
( (TC-SC-STC)/H) - SC - STC = C/H + C
( (TC-SC-STC)/H) - SC - STC = C * (H+1)/H (factoring out H)
( ( (TC-SC-STC)/H) - SC - STC) / ( ( (H +1) /H ) = C

Simplifying the terms, we get:

((TC-SC-STC) - H*(SC+STC)) / (H + 1) = C

If the value of B changes, plug that into the equation to find the new value of C

((B-SC-STC) - H*(SC+STC)) / (H + 1) = C

If that doesn't make sense, Chris, email me and I'll send you a revised spreadsheet.  

serenity blaze
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since 2000-02-02
Posts 27738

3 posted 2005-01-20 08:11 PM


*shudder*
Balladeer
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since 1999-06-05
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4 posted 2005-01-20 11:15 PM


Ron took the words right out of my mouth!!
serenity blaze
Member Empyrean
since 2000-02-02
Posts 27738

5 posted 2005-01-20 11:26 PM


Nod.

Yep.

That woulda been my second guess.


Christopher
Moderator
Member Rara Avis
since 1999-08-02
Posts 8296
Purgatorial Incarceration
6 posted 2005-01-23 04:06 AM


very, very cool.

it worked no problem, makes my life much eaiser to be sure.

one question (and this may be one of the places where i got myself stuck) - what does adding 1 to H do when factoring it out?

thank you, Ron.

egowhores.com - really love yourself.

Ron
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Member Rara Avis
since 1999-05-19
Posts 8669
Michigan, US
7 posted 2005-01-23 08:00 PM


We had to factor C/H+C, of course, so C could be isolated from H.

C/H + C
C/H + C/1 [this is where the 1 will come from, but we want to multiply instead so ...]
(C * 1/H) + (C* 1/1) [with C on both sides we can now factor C to isolate it]
C * (1/H + 1/1) [which can then be simplified to ... ]
C * (1/H + 1) [could have actually stopped here]
C * (H+1)/H [but tightening the parens seemed a bit cleaner to me]

That final simplification has a name (Law of Unity?), but really is just the way Unity always works ...

1/2 + 1/1 = (2+1)/2 = 3/2
1/3 + 1/1 = (3+1)/3 = 4/3
1/4 + 1/1 = (4+1)/4 = 5/4



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