MathChapter 12: Composition, Recursion, and Exponential Functions
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Card 1 of 20. Answer hidden.
Prompt
What model represents per-period growth at decimal rate \(r\)?
Answer
\(A=P(1+r)^t\).
Prompt
What model represents per-period decay at decimal rate \(r\)?
Answer
\(A=P(1-r)^t\).
Prompt
What multiplier represents a \(6\%\) increase?
Answer
\(1.06\).
Prompt
What multiplier represents a \(12\%\) decrease?
Answer
\(0.88\).
Prompt
How is \(4.5\%\) written as a decimal rate?
Answer
\(0.045\).
Prompt
What does \(P\) represent in these models?
Answer
The initial amount, which the model returns at \(t=0\).
Prompt
What does \(t\) represent in \(P(1\pm r)^t\)?
Answer
The number of periods matching the stated rate.
Prompt
What is the doubling-time model?
Answer
\(A=P\cdot2^{t/d}\).
Prompt
What does \(t/d\) count in a doubling model?
Answer
The number of doubling intervals elapsed.
Prompt
What is the half-life model?
Answer
\(A=P(\frac12)^{t/d}\).
Prompt
What does one half-life do to the current amount?
Answer
It multiplies the amount then remaining by \(\frac12\).
Prompt
After three doubling intervals, what multiple of \(P\) remains?
Answer
\(8P\).
Prompt
After four half-lives, what fraction of \(P\) remains?
Answer
\(\frac{P}{16}\).
Prompt
Must \(t/d\) be a whole number?
Answer
No. Fractional numbers of doubling or half-life intervals are valid.
Prompt
Why is \(P(0.06)^t\) wrong for \(6\%\) growth?
Answer
It uses only the added fraction; growth must retain the original amount with factor \(1.06\).
Prompt
How should two model values be compared accurately?
Answer
Evaluate both with full precision at the requested time, subtract, then round once.
Prompt
A quantity doubles every \(5\) years. What exponent is used after \(12\) years?
Answer
\(12/5=2.4\).
Prompt
A sample has half-life \(8\) days. What exponent is used after \(20\) days?
Answer
\(20/8=2.5\).
Prompt
What two substitutions quickly validate a doubling model?
Answer
Check \(A(0)=P\) and \(A(d)=2P\).
Prompt
What two substitutions quickly validate a half-life model?
Answer
Check \(A(0)=P\) and \(A(d)=P/2\).
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