Answer: Percent change = 20%
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Work Shown:
A = old value = 25 (last week's number)
B = new value = 30 (current week's number)
C = percent change
C = [ (B-A)/A ] * 100%
C = [ (30-25)/25 ] * 100%
C = [ 5/25 ] * 100%
C = 0.20* 100%
C = 20%
The percent change is 20%
The positive value of C indicates we have a percent increase.
I see your last line is : c(x) = 0.9(x^2-10)^2 + 101.1
Let y = x^2, then c(y) = 0.9(y-10)^2 + 101.1
Apparently, c(y) is a parabola, min is 101.1 when y = 10, max is infinity
So let x^2 = 10 -> x = sqrt(10) or -sqrt(10), min is 101.1, max is infinity
I think Ollie payed $1,500 back.
The answer should be the opposite. equaling 0. so 5.
-5 + 5