Suppose you deposit $2500 in a savings account that pays you 5% interest per year. (Calculator)

(a) How many years will it take for you to double your money?

Respuesta :

Answer:

14.20669 years

Roughly 14 years and 2.5 months.

Step-by-step explanation:

Assuming this is compound interest.

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

[tex]A=[/tex] Final Amount

[tex]P=[/tex] Principal Amount

[tex]r=[/tex] Interest Rate

[tex]n=[/tex] # of times interest is compounded per year

[tex]t=[/tex] Time in years

We are looking for the times in years to double the money so

[tex]2500*2=5000[/tex]

[tex]A=5000[/tex]

[tex]P=2500[/tex]

[tex]r=0.05[/tex]

[tex]n=1[/tex]

[tex]t=?[/tex]

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

Step 1.

Plug in our numbers into the compound interest formula.

[tex]5000=2500(1+\frac{0.05}{1}) ^{1*t}[/tex]

Step 2.

Simplify the equation.

Evaluate [tex]1+\frac{0.05}{1}=1.05[/tex]

Evaluate [tex]1*t=t[/tex]

[tex]5000=2500(1.05) ^{t}[/tex]

Step 3.

Divide both sides of the equation by [tex]2500[/tex]

[tex]\frac{5000}{2500}=1.05 ^{t}[/tex]

Evaluate [tex]\frac{5000}{2500}=2[/tex]

[tex]2=1.05 ^{t}[/tex]

Step 4.

Take the natural log of both sides of the equation and rewrite the right side of the eqaution using properties of exponents/logarithms.

[tex]ln(2)=t*ln(1.05)[/tex]

Step 5.

Divide both sides of the equation by [tex]ln(1.05)[/tex]

[tex]\frac{ln(2)}{ln(1.05)}=t[/tex]

Step 6.

Evaluate

[tex]t=14.20669[/tex]

Roughly 14 years and 2.5 months.

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