Calvin deposits $400 in a savings account that accrues 5% interest compounded monthly. After c years, Calvin has
$658.80. Makayla deposits $300 in a different savings account that accrues 6% interest compounded quarterly. After m
years, Makayla has $613.04. What is the in approximate difference in the number of years that Calvin and Makayla have
their money invested?
O Makayla invests her money 1 year longer.
O Makayla invests her money 2 years longer.
O Calvin invests his money 1 year longer.
O Calvin invests his money 2 years longer.

Respuesta :

Answer:

Dot number 2. Makayla invests her money 2 years longer.

Step-by-step explanation:

Calvin 400$ with 5% interest compounded monthly will get you to 666.0294029241$ after 13 months or 1 year and 1 month

Makayla 300$ with 6% interest quarterly

1st year 378.743088$(4 quarters)

2nd year 478.1544223592$(+4 quarters)

3rd year 603.6589415506$(+4 quarters)

3rd year and 1 quarter 639.8784780436$

Answer:

So the second option is the answer: Makayla invests her money 2 years longer.

Step-by-step explanation:

Formula for compound interest: [tex]A=P(1+\frac{r}{n})^{nt}[/tex]

Calvin:

[tex]A=658.80[/tex]

[tex]P=400[/tex]

[tex]r=0.05[/tex]

[tex]n=12[/tex]

[tex]t=?[/tex]

Makayla:

[tex]A=613.04[/tex]

[tex]P=300[/tex]

[tex]r=0.06[/tex]

[tex]n=4[/tex]

[tex]t=?[/tex]

Lets solve for [tex]t[/tex].

1)  Divide both sides of the equation by [tex]P[/tex].

[tex]\frac{A}{P} =(1+\frac{r}{n})^{nt}[/tex]

2)  Take the natural log of both sides.

[tex]ln(\frac{A}{P}) =ln((1+\frac{r}{n})^{nt})[/tex]

3)  Rewrite the right side of the equation using properties of exponents.

[tex]ln(\frac{A}{P}) =nt*ln(1+\frac{r}{n})[/tex]

4)  Divide each side of the equation by [tex]n*ln(1+\frac{r}{n})[/tex]

[tex]\frac{nt*ln(1+\frac{r}n)}{n*ln(1+\frac{r}n)}=\frac{ln(\frac{A}{P})}{n*ln(1+\frac{r}n)}[/tex]

5)  Cancel the common factor [tex]n[/tex] on the left side of the equation.

[tex]\frac{t*ln(1+\frac{r}n)}{ln(1+\frac{r}n)}=\frac{ln(\frac{A}{P})}{n*ln(1+\frac{r}n)}[/tex]

6)  Cancel the common factor of [tex]ln(1+\frac{r}{n})[/tex].

[tex]t=\frac{ln(\frac{A}{P)}}{n*ln(1+\frac{r}{n})}[/tex]

Now we have an equation for [tex]t[/tex] that we can use to answer your question.

For Calvin:

[tex]t=\frac{ln(\frac{658.80}{400)}}{12*ln(1+\frac{0.05}{12})}[/tex]

[tex]t=10[/tex]

For Makayla:

[tex]t=\frac{ln(\frac{613.04}{300)}}{3*ln(1+\frac{0.06}{3})}[/tex]

[tex]t=12[/tex]

So the second option is the answer: Makayla invests her money 2 years longer.

Note: This question took me 2 minutes to answer but typing it took 30. lol