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March 25th, 2015, 07:17 PM  #1 
Newbie Joined: Mar 2015 From: San Francisco Posts: 2 Thanks: 1  How to Calculate the amount if you know the total and percentage
Hello newbie here. Long story short looking for a crash course on Algebra, its been a while since I geared my brain up for math, but I have taken up to Statistics, let me know if you guys know of any online Algebra course? here is what I currently have in mind. If I know a percentage increase of an amount, how do I figure how much the number was increased by. The dollar amount is 19,244 and percentage increase is 63.2, how do I calculate how much X was increased by to get to dollar of 19,244? Last edited by dado123; March 25th, 2015 at 07:24 PM. 
March 25th, 2015, 07:25 PM  #2 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs 
If $X$ is the original amount, and we increase it by 63.2% and get 19244, then we may write: $\displaystyle 1.632X=19244$ Hence: $\displaystyle X=\frac{19244}{1.632}=\frac{35375}{3}= 11791.\overline{6}$ And so the increase in $X$ is: $\displaystyle \Delta X=19244\frac{35375}{3}=\frac{22357}{3}=7452.\overline{3}$ 
March 25th, 2015, 07:30 PM  #3 
Newbie Joined: Mar 2015 From: San Francisco Posts: 2 Thanks: 1 
Thanks, can you please expand on how the percentage of 63.2 when to be written as 1.632?

March 25th, 2015, 07:42 PM  #4 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs 
If we take some quantity $X$ and increase if by 63.2%, we are adding to $X$ a quantity that is equal to 63.2% of $X$: $\displaystyle X+63.2\%\cdot X$ Now, the percentage symbol is shorthand for $\displaystyle \frac{1}{100}$ as it means per (for each) centum (100), and when we divide by 100, we move the decimal point two places to the left, so we have: $\displaystyle X+0.632X$ Now, we may factor out $X$ since it is a common factor in both terms: $\displaystyle X(1+0.632)$ Combining the two numbers and putting them in front of the variable as is traditional and allowed by the commutativity of multiplication (this just means $a$ times $b$ is the same as $b$ times $a$), we have: $\displaystyle 1.632X$ Does this make sense? 

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