How do I solve for X and Y?

Javery

Javery

CAGiversary!
Feedback
20 (100%)
X/(4,567,881+X+(125,000/Y)) = .082

8,000,000/(4,567,881+X+(125,000/Y)) = Y

Can anyone put this in EXCEL? What formulas would I use? I know there are 2 variables so 2 equations make them solvable but my algebra is super rusty...
 
One set of numbers that will get the outcome you're looking for is:
X = 420000
Y = 1.57

I'm sure there are other combinations. But that's just me playing around in excel.
 
[quote name='Quillion']One set of numbers that will get the outcome you're looking for is:
X = 420000
Y = 1.57

I'm sure there are other combinations. But that's just me playing around in excel.[/QUOTE]

How did you set this up in Excel? Those numbers are really close to what I was thinking they were.
 
[quote name='Javery']How did you set this up in Excel? Those numbers are really close to what I was thinking they were.[/QUOTE]

I just typed the the equations, and fiddled with inputs till they started to match. Nothing special.

Cell C5 contains: =C2/(4567881+C2+(125000/C3))
Cell C6 contains: =8000000/(4567881+C2+(125000/C3))
And Cell C2 represents X Cell C3 represents Y.

I kept changing the numbers in C2 and C3 until C6 equalled .082 and C7 was roughly equal to C3.

My final (better) outcome was:
X = 415,100
Y = 1.58

C5 (equation 1) = 0.082001623
C6 (equation 2) = 1.580373367

That's almost dead on. Not terribly scientific, though.
 
[quote name='Ugamer_X']Math and science have a well-known liberal bias.[/QUOTE]

Exactly. Plus this is where all the crazy people on the forums congregate and since scientists and mathematicians are usually crazy in some form or another it only made sense. :D

Thanks Qulllion - I'm trying to duplicate your effort in Excel right now...
 
first off, why would you want to use EXCEL to solve this? EXCEL gives numerical answers precise up to 16 decimal places. so if you want a general solution (which would be ideal), it would be best to set it up algebraically.

second, can you explain the context in which you would like to solve this? basically state the problem.

if I had solver, I would be able to give a better (precise) EXCEL answer.
doing a quick "run", I found
x = 418662.026142706
y = 1.57924350064662

Javery, not to belittle Quillion's help but I would set the equations equal to zero.

this system is "difficult" to solve is because the equations are nonlinear. you know what, I'll go find an online nonlinear equation calculator...

okay didn't find any decent ones online and I rather not try to writeup something in matlab...

here's what entering on wolfram alpha yielded:
http://www.wolframalpha.com/input/?i=x%2F%284567881+%2B+x+%2B+125000%2Fy+%29+-+0.082+%3D+0%3B+8000000%2F%284567881+%2B+x+%2B+125000%2Fy%29+-+y+%3D0

so coordinating to wolfram alpha, x is arbitrary such that x is NOT equal to 4567881 and y = 7875000/ (x + 4567881)
 
actually the algebra is not as bad as I thought.

one way to solve:
rearrange the first equation and solve in terms of y. rearrange the second equation and solve in terms of x. substitute one variable from one equation and plugin to the other, solving for the other variable.

okay hopefully my quick scrap work is correct:
y = 125000/( 0.918x/0.082 - 4567881)
x = 7875000/y - 4567881


also what Quillion had in mind is actually what many programs do. the program will iterate based on a set increment value until the conditions are met or found. Javery if you like, I can walk you through a "simple" EXCEL method assuming you have the SOLVER addon installed (if not go to Tools and Addons and make sure it is checked, if you have 2007 or 2010 version Google how to install it. if that doesn't work then that means you'll need the microsoft office cd). just send me a pm
 
You must log in or register to reply here.
bread's done
Back
Top