Paisley invested $3,000 in an account paying an interest rate of 3% compounded
continuously. Maya invested $3,000 in an account paying an interest rate of 4%
compounded daily. To the nearest hundredth of a year, how much longer would it
take for Paisley's money to triple than for Maya's money to triple?

Respuesta :

Answer:

9.15 years

Step-by-step explanation:

step 1

Paisley

we know that

The formula to calculate continuously compounded interest is equal to

[tex]A=P(e)^{rt}[/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  

e is the mathematical constant number

we have  

[tex]t=?\ years\\ P=\$3,000\\ r=0.03\\A=\$9,000[/tex]  

substitute in the formula above

[tex]9,000=3,000(e)^{0.03t}[/tex]  

solve for t

[tex]3=(e)^{0.03t}[/tex]  

apply ln both sides

[tex]ln(3)=ln(e)^{0.03t}[/tex]  

[tex]ln(3)=(0.03t)ln(e)[/tex]  

[tex]ln(3)=(0.03t)[/tex]  

solve for t

[tex]t=ln(3)/(0.03)[/tex]  

[tex]t=36.62\ years[/tex]

step 2

Maya

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=\$3,000\\ r=0.04\\A=\$9,000\\n=365[/tex]  

substitute in the formula above

[tex]9,000=3,000(1+\frac{0.04}{365})^{365t}[/tex]  

solve for t

[tex]3=(\frac{365.04}{365})^{365t}[/tex]

Apply log both sides

[tex]log(3)=log(\frac{365.04}{365})^{365t}[/tex]

[tex]log(3)=(365t)log(\frac{365.04}{365})[/tex]

[tex]t=log(3)/[(365)log(\frac{365.04}{365})][/tex]

[tex]t=27.47\ years[/tex]

step 3

we know that

To find out how much longer would it  take for Paisley's money to triple than for Maya's money to triple find the difference in years

[tex]36.62-27.47=9.15\ years[/tex]