chapter 5 quiz\nscore: 12/20 answered: 3/5\nquestion 2\nrenee wants to invest $2100 in a savings account…

Explanation:

Step1: Identify the simple - interest formula

The simple - interest formula is $A = P(1+rt)$, where $A$ is the final amount, $P$ is the principal amount, $r$ is the interest rate, and $t$ is the time in years. Since the investment doubles, $A = 2P$, $P$ is the initial investment, $t = 12$ years.

Step2: Substitute values into the formula

Substitute $A = 2P$ and $t = 12$ into $A = P(1+rt)$: [ \begin{align*} 2P&=P(1 + 12r)\ 2&=1 + 12r \end{align*} ]

Step3: Solve for $r$

Subtract 1 from both sides: $2−1=12r$, so $1 = 12r$. Then $r=\frac{1}{12}\approx0.0833$.

Step4: Convert to percentage

To convert $r$ to a percentage, multiply by 100: $r = 0.0833\times100 = 8.33%$. Rounding to the nearest tenth of a percent, $r\approx8.3%$.

Answer:

$8.3$