David W. answered • 03/03/18
Tutor
4.7
(90)
Experienced Prof
"How to calculate percentage change
To calculate percentage change (increase or decrease):
Calculate the difference between the two numbers being compared:
Difference = New Number - Original Number
Divide the difference by the original number and multiply the result by 100:
Percentage Change = Difference ÷ Original Number × 100
To calculate percentage change (increase or decrease):
Calculate the difference between the two numbers being compared:
Difference = New Number - Original Number
Divide the difference by the original number and multiply the result by 100:
Percentage Change = Difference ÷ Original Number × 100
If the final answer is a negative number it is a percentage decrease, otherwise, it is a percentage increase.
Example: Calculate the percent change from 2 to 10
Find the difference: 10 - 2 = 8.
Divide the difference by the original number: 8 / 2 = 4.
Multiply the result by 100: 4 * 100 = 400%.
The answer is a percentage increase of 400%." -- Bing.com
Special Note: These calculations assume that the number values are linear. That is, the difference between a 2 and a 3 is the same as the difference between a 3 and a 4, for example. "A scale of 1-10" may or may not have a constant meaning for the same difference between values. If differences are not consistent, percent difference is also not meaningful. An additional consideration with "a scale of 1-10" is the meaning of 1 and of 10. If 1 means literally dead, and 10 means the absolute best humanly possible, then these numbers represent conditions. Otherwise, they are simply numbers. If 6 is not twice as good as 3 and if 8 is not twice as good as 4 and if 10 is not twice as good as 5, etc., then these numbers are merely qualitative categories, not quantitative measurements. The value 245 pounds is a quantitative measurement, but "overweight" is a qualitative assessment.
Mathematically, an improvement of 100% means "twice as good."
Janet J.
03/03/18