On your ninth birthday, you received $300 which you invested at 4.5 percent interest, compounded annually. your investment is now worth $756. how old are you today?

Respuesta :

300(1+0.045)^n = 756

1.045^n = 756/300= 2.52

n = 21 year

Your age = 9+21 = 30


Answer:

30 years

Step-by-step explanation:

On your ninth birthday, you received $300 which you invested at 4.5 percent interest, compounded annually.

Principal amount is $300

rate of interest is 4.5%

your investment is now worth $756. So amount after t year is $756

We use compound interest formula

[tex]A=P(1+r)^t[/tex]

A is the final amount

P is principal amount

r is the rate of interest 0.045

t is the number of years

Plug in the values in the formula

[tex]756=300(1+0.045)^t[/tex]

Divide both sides by 300

[tex]\frac{756}{300}=1. 045^t[/tex]

Take ln on both sides

[tex]ln\frac{756}{300}=t ln(1. 045)[/tex]

Divide both sides by ln(0.045)

t= 20.99= 21 years

9 years + 21 years = 30 years

She is 30 years old now