Solve the problem.
-The interest I earned in $1 \mathrm{yr}$ on a fixed principal varies directly as the interest rate $\mathrm{r}$. An investment earns $\$ 54.53$ at an interest rate of $4.15 \%$. Find an equation of variation.
A) $I=-\frac{415}{5453} r$
B) $\mathrm{I}=\frac{415}{5453} \mathrm{r}$
C) $I=\frac{2519}{50} \mathrm{r}$
D) $I=\frac{5453}{415} r$

Question

Quizplus · Accepted Answer

The equation of variation is $I = k \cdot r$, where $k$ is the constant of variation. Given $I = 54.53$ when $r = 4.15$, we find $k = \frac{54.53}{4.15}$, which simplifies to $\frac{5453}{415}$. Thus, the equation is $I = \frac{5453}{415} r$.

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