Answer:
It will take 36.1 years for her money to reach $105,000.
Step-by-step explanation:
The amount of money earned after t years in continuous interest is given by:
[tex]P(t) = P(0)e^{rt}[/tex]
In which P(0) is the initial investment and r is the interest rate, as a decimal.
Anna invests $7,000 in an account that compounds interest continuously and earns 7.5%.
This means that [tex]P(0) = 7000, r = 0.075[/tex]
How long will it take for her money to reach $105,000?
This is t for which P(t) = 105000.
[tex]P(t) = P(0)e^{rt}[/tex]
[tex]105000 = 7000e^{0.075t}[/tex]
[tex]e^{0.075t} = \frac{105000}{7000}[/tex]
[tex]e^{0.075t} = 15[/tex]
[tex]\ln{e^{0.075t}} = \ln{15}[/tex]
[tex]0.075t = \ln{15}[/tex]
[tex]t = \frac{\ln{15}}{0.075}[/tex]
[tex]t = 36.1[/tex]
It will take 36.1 years for her money to reach $105,000.
