SOLUTION: Percent of Change is what we are doing at this time. I do not understand this at all. State whether each percent of change is a percent of increase or a percent of decrease.

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Question 18745: Percent of Change is what we are doing at this time. I do not understand this at all.
State whether each percent of change is a percent of increase or a percent of
decrease. Then find each percent of change. Round to the nearest whole percent.
problem 1. original: 50
New: 70 Please explain this to me.
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Well, first you'll notice that there is an increase, right? Because 70 is more than 50. And the amount of the increase is: the new value minus the old value, or 70 - 50 = 20.
So, the amount of increase is 20.
The question is now, what percentage of the old value (50) is the amount of increase (20)? Remember that percent means out of 100.
You can find out by using proportions...remember those?
20%2F50+=+x%2F100 Solve for x. Multiply both sides by 100 and simplify.
%28100%29%2820%29%2F50+=+x
x+=+40
The answer is: 40% increase.
If you like formulas better, then here's the formula:
Let N = new value, O = old value:
Percent change = %28%28N+-+O%29%2FO%29%28100%29 If this is positive, then it's an increase. If it's negative, then it's a decrease.
Let's see if this works for your problem:
N = 70, O = 50
Percent change = %28%2870+-+50%29%2F%2850%29%29%28100%29 = %2820%29%28100%29%2F50+=+%2820%29%282%29 = 40% and it's positive so it's an increase.