This page says-
absolute change = new quantity – old quantity.
For ex-
Example 1: On September 20, a gallon of gas at my usual gas station cost $1.83. On September 30, I noticed that the price had gone down to $1.65 per gallon.
The absolute change in the price of gas between September 20 and September 30 is
1.65 – 1.83 = - 0.18 dollars per gallon
We say that the price of gas decreased by $0.18 (or 18 cents).
And this page also says
Percentage change = absolute change/original quantity*100
Example 1 revisited: On September 20, a gallon of gas at my usual gas station cost $1.83. On September 30, I noticed that the price had gone down to $1.65 per gallon.
The percentage change in the price of gas between September 20 and September 30 is
(1.65 – 1.83) 100 = – 0.18(100) = -18% per gallon
We say that the price of gas decreased by 18% per gallon.
But from the formula of percentage change I can see that they are not dividing it by origianl quantity.
Is this right?
Please help me figure out.
Best Answer
It should be $\frac {1.65-1.83}{1.83}100\%\approx 9.8\%$ The definition you have quoted is clear.