16Hit1600
Advanced MathEasy–MediumPercent change between consecutive outputs of a decay model

Advanced Math practice question

The function p is defined by p(t) = 500(0.8)ᵗ. By what percent does p decrease from t = 1 to t = 2?

Answer: 20

Each unit increase in t multiplies p by 0.8, a 20% decrease. (p(1) = 400 and p(2) = 320: a drop of 80, which is 20% of 400.)

Common wrong answers

If you answered 8
8 mistakes 0.8 for 8%.
If you answered 36
36 is the percent drop over two steps, from p(0) = 500 to p(2) = 320.
If you answered 80
80 is the drop in value, not the percent.

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