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It recently happened to me:

My original accept rate on one of the stackexchange websites was 62% , but after going back to an old question and accepting an answer there- it got raised to 65%.

So is there a way to find the total number of questions asked by me?

I've come up with this:

original accepted answers=x

total questions answered=y [ignoring the unanswered ones, because that's what I think stackexchange's algorithm does]

so x/y=62

On accepting an answer it got raised to 65, so

(x+1)/y=65

Is it right? It gave me a fraction less than 1.

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1 Answer

You have a problem with units. $x$ and $y$ are whole numbers, but $62$ and $65$ are percentages and should be expressed as $0.62$ and $0.65$. Also you lost something when you wrote x+1/=65. Maybe you started with $(x+1)/y=65$ and later read it as $x+(1/y)=65$?

You have $\frac xy=0.62$ and $\frac {x+1}y=0.65$. Subtracting we get $\frac 1y=0.03$, so $y=\frac {100}3$. Since $y$ must be a whole number, there must be some rounding on the percentages. Taking $y=33$ would give $x=20.46$ in the first equation. You can play with values nearby to see if you can find an $x$ that is closer to a whole number. This shows the inaccuracy of the subtraction-you can think we really got $y = 0.03 \pm 0.01$ which is a large possible error.

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How'd you get y=0.03±0.01? Don't understand where you got the 0.01 from? –  Ghost Dec 12 '12 at 17:36
    
@Ghost: I got it because I assume the $0.65$ is rounded to two decimals and could really be anywhere between $0.645$ and $0.655$. Similarly the $0.62$ is really somewhere between $0.615$ and $0.625$. Subtracting $0.655-0.615$ gives $0.04$, while taking the other ends gets $0.02$ –  Ross Millikan Dec 12 '12 at 17:38
    
@ Ross Millikan sorry I dont really understand the concept- 0.65 is a percentage, why even take a range between 0.645 and 0.655 –  Ghost Dec 12 '12 at 17:41
    
@Ghost: Suppose you had accepted $2$ out of $3$ questions. The correct percentage would be $66.66666\ldots \%$ The site would probably round that to $67\%$ (at least all the percentages I have seen are whole numbers). If you had accepted $337$ out of $500$ the correct percentage would be $67.4\%$ but would probably be reported as $67\%$ as well. –  Ross Millikan Dec 12 '12 at 17:46
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