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Math Problem Up for Grabs |

Christopher
Moderator
Member Rara Avis
since 1999-08-02
Posts 8296Purgatorial Incarceration |
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. |
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Christopher
Moderator
Member Rara Avis
since 1999-08-02
Posts 8296Purgatorial Incarceration |
here's an Excel spreadsheet as an example for the base equation. http://egowhores.com/temp/Sample.xls |
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Ron
Administrator
Member Rara Avis
since 1999-05-19
Posts 8669Michigan, US |
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) = CIf that doesn't make sense, Chris, email me and I'll send you a revised spreadsheet. |
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serenity blaze Member Empyrean
since 2000-02-02
Posts 27738 |
*shudder* |
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Balladeer
Administrator
Member Empyrean
since 1999-06-05
Posts 25505Ft. Lauderdale, Fl USA |
Ron took the words right out of my mouth!! |
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serenity blaze Member Empyrean
since 2000-02-02
Posts 27738 |
Nod. Yep. That woulda been my second guess. |
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Christopher
Moderator
Member Rara Avis
since 1999-08-02
Posts 8296Purgatorial Incarceration |
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 - |
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Ron
Administrator
Member Rara Avis
since 1999-05-19
Posts 8669Michigan, US |
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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