You decide to put $2000 in a savings account to save for a $3000 down payment on a new car. If the account has an interest rate of 4% per year and is compounded monthly, how long does it take until you have $3000 without depositing any additional funds?

Respuesta :

Answer:

[tex]t=10.2\ years[/tex]      

Step-by-step explanation:

we know that    

The compound interest formula is equal to  

[tex]A=P(1+\frac{r}{n})^{nt}[/tex]  

where  

A is the Final Investment Value  

P is the Principal amount of money to be invested  

r is the rate of interest  in decimal

t is Number of Time Periods  

n is the number of times interest is compounded per year

in this problem we have  

[tex]t=?\ years\\P=\$2,000\\A=\$3,000\\ r=0.04\\n=12[/tex]  

substitute in the formula above  

[tex]3,000=2,000(1+\frac{0.04}{12})^{12t}[/tex]

[tex]1.5=(\frac{12.04}{12}})^{12t}[/tex]    

Applying log both sides

[tex]log(1.5)=log[(\frac{12.04}{12}})^{12t}][/tex]

[tex]log(1.5)=(12t)log(\frac{12.04}{12})[/tex]

[tex]t=log(1.5)/[(12)log(\frac{12.04}{12})][/tex]  

[tex]t=10.2\ years[/tex]