what is x in "x + (x * .11416) = 442.42" **Resolved**

**msimmons** · Oct 4th, 2002, 10:31 AM

what is x in "x + (x * .11416) = 442.42"
thanks
Michael

**msimmons** · Oct 4th, 2002, 10:46 AM

k the answer is 397.09 but I only got to that by trial and error... what is the formula to get this?
TIA
Michael

**DiGiTaIErRoR** · Oct 4th, 2002, 11:00 AM

Subtract an x from each side

so .11416x = 442.42-x

add x to each side

1.11416x=442.42

x=442.42/1.11416

**DiGiTaIErRoR** · Oct 4th, 2002, 11:02 AM

The answer is technically:

397.08838945932361599770230487542

**msimmons** · Oct 4th, 2002, 11:06 AM

Thanks!
Michael

**msimmons** · Oct 4th, 2002, 11:22 AM

Originally posted by DiGiTaIErRoR
The answer is technically:

397.08838945932361599770230487542

this is money so we are rounding to the next cent.

does
(x * .11416)
mean the same exact thing as
.11416x
?

thanks again
Michael

**DiGiTaIErRoR** · Oct 4th, 2002, 12:25 PM

Yes.

**msimmons** · Oct 4th, 2002, 12:44 PM

cool thanks again.
Math is what is keeping me from persuing my BS.

**SilverSprite** · Oct 4th, 2002, 03:27 PM

Ok so why did you subtract x then add x to both sides digitalerror? Was there a point to that?

**DiGiTaIErRoR** · Oct 4th, 2002, 03:47 PM

I was only halfassed thinking.

**jim mcnamara** · Oct 4th, 2002, 04:59 PM

Code:

simpler approach
x + ( x * .11416) = 442.42
Add the "x" side together
1.11416 * x = 442.42
x = 442.42/1.11416
x= 397.09   (rounded)

397.09 is THE correct result because you cannot have more digits of precision answer than exist in the least precise number -- 5 digits - in the input values.

**siyan** · Oct 4th, 2002, 09:29 PM

Originally posted by jim mcnamara

Code:

simpler approach x + ( x * .11416) = 442.42 Add the "x" side together 1.11416 * x = 442.42 x = 442.42/1.11416 x= 397.09 (rounded)

397.09 is THE correct result because you cannot have more digits of precision answer than exist in the least precise number -- 5 digits - in the input values.

in math you assume the given numbers in the question are exact.

of course if he came up with 0.11416 and/or 442.42 then yeah...

-C

**Kalkewl8ter** · Oct 25th, 2002, 10:23 PM

Trial and error for a question like this??? How long did that take you?!

**msimmons** · Oct 28th, 2002, 09:38 AM

maybe 10 min's.

**Kalkewl8ter** · Oct 29th, 2002, 08:42 PM

Wow, I would have guessed about an hour. If you can try 397.09 within ten minutes, you must be a psychic...

**msimmons** · Oct 29th, 2002, 10:34 PM

lol...
if you look at the times of the first two posts it is 15 mins apart. I guess I'm an idot savant (no wonder I passed all my math and still suck at it).

**jim mcnamara** · Nov 4th, 2002, 10:08 AM

Siyan -

FWIW - you should consider significant digits or accuracy in computational mathematics - what that his algebra problem was.

Please, See this site

http://mathworld.wolfram.com/SignificantDigits.html

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