Respuesta :
[tex]\bf \begin{array}{ccll}
\stackrel{t}{months}&\stackrel{A}{books}\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
0&80\\
1&100\\
2&125
\end{array}[/tex], we know that on Month 0, the Books were 80
[tex]\bf \qquad \textit{Amount for Exponential Growth}\\\\ A=I(1 + r)^t\qquad \begin{cases} A=\textit{accumulated amount}\to &80\\ I=\textit{initial amount}\\ r=rate\to r\%\to \frac{r}{100}\\ t=\textit{elapsed time}\to &0\\ \end{cases} \\\\\\ 80=I(1+r)^0\implies 80=I\qquad therefore\qquad \boxed{A=80(1+r)^t}[/tex]
we also know that on the first month there were 100 books,
[tex]\bf \qquad \textit{Amount for Exponential Growth}\\\\ A=I(1 + r)^t\qquad \begin{cases} A=\textit{accumulated amount}\to &100\\ I=\textit{initial amount}\\ r=rate\to r\%\to \frac{r}{100}\\ t=\textit{elapsed time}\to &1\\ \end{cases} \\\\\\ 100=80(1+r)^1\implies \cfrac{100}{80}=1+r\implies \cfrac{5}{4}=1+r \implies \cfrac{5}{4}-1=r \\\\\\ \cfrac{1}{4}=r\implies 0.25=r\qquad therefore\qquad \boxed{A=80(1+0.25)^t}[/tex]
now, how many books when t = 8? A=80(1+0.25)⁸, or A=80(1.25)⁸.
[tex]\bf \qquad \textit{Amount for Exponential Growth}\\\\ A=I(1 + r)^t\qquad \begin{cases} A=\textit{accumulated amount}\to &80\\ I=\textit{initial amount}\\ r=rate\to r\%\to \frac{r}{100}\\ t=\textit{elapsed time}\to &0\\ \end{cases} \\\\\\ 80=I(1+r)^0\implies 80=I\qquad therefore\qquad \boxed{A=80(1+r)^t}[/tex]
we also know that on the first month there were 100 books,
[tex]\bf \qquad \textit{Amount for Exponential Growth}\\\\ A=I(1 + r)^t\qquad \begin{cases} A=\textit{accumulated amount}\to &100\\ I=\textit{initial amount}\\ r=rate\to r\%\to \frac{r}{100}\\ t=\textit{elapsed time}\to &1\\ \end{cases} \\\\\\ 100=80(1+r)^1\implies \cfrac{100}{80}=1+r\implies \cfrac{5}{4}=1+r \implies \cfrac{5}{4}-1=r \\\\\\ \cfrac{1}{4}=r\implies 0.25=r\qquad therefore\qquad \boxed{A=80(1+0.25)^t}[/tex]
now, how many books when t = 8? A=80(1+0.25)⁸, or A=80(1.25)⁸.
Hello, The answer to this problem is 477
How i got it;
Well were using the formula
A(t)=b(1+r)^t
Now all we have to do it fill in the blanks.
So when doing so its A=80(1+0.25)^t
t=8
1+.25=1.25
A=80(1.25)^8
Not do the math and theirs your answer!
Answer: 476.837 rounded to 477
Hope this helps!