A person invests in an account with interest compounded continuously according to the formula

[tex]A=f(t)=8900 e^{0.057 t}[/tex]

where [tex]A[/tex] is the amount in the account and [tex]t[/tex] is in years.

1. Find [tex]f(0)[/tex]: [tex]$\boxed{\,}$[/tex]

2. To the nearest cent, find the amount in the account after 8 years: [tex]$\boxed{\$[/tex]\,}[tex]$

3. To the nearest tenth of a year, determine how long it will take for the investment to grow to $[/tex]13,100: \boxed{\,}$ years



Answer :

Sure, let's solve this step by step.

1. Finding [tex]\( f(0) \)[/tex]:

[tex]\( f(t) \)[/tex] represents the amount in the account at time [tex]\( t \)[/tex], and is given by the formula:

[tex]\[ A = f(t) = 8900 e^{0.057 t} \][/tex]

To find [tex]\( f(0) \)[/tex], we simply substitute [tex]\( t = 0 \)[/tex] into the formula:

[tex]\[ f(0) = 8900 e^{0.057 \cdot 0} = 8900 e^0 \][/tex]

Since [tex]\( e^0 = 1 \)[/tex]:

[tex]\[ f(0) = 8900 \cdot 1 = 8900 \][/tex]

So, [tex]\( f(0) = \$8900.00 \)[/tex].

2. Finding the amount in the account after 8 years:

We need to find [tex]\( f(8) \)[/tex], so we substitute [tex]\( t = 8 \)[/tex] into the formula:

[tex]\[ f(8) = 8900 e^{0.057 \cdot 8} \][/tex]

After performing the calculation, the amount in the account after 8 years is approximately:

[tex]\[ f(8) = \$14041.98 \][/tex]

3. Determining the time it will take for the investment to grow to \[tex]$13100: We need to find \( t \), given that \( A = \$[/tex]13100 \):

[tex]\[ 13100 = 8900 e^{0.057 t} \][/tex]

First, we isolate the exponential term by dividing both sides by 8900:

[tex]\[ \frac{13100}{8900} = e^{0.057 t} \][/tex]

Simplifying the left-hand side:

[tex]\[ \frac{13100}{8900} \approx 1.4719 \][/tex]

So, we have:

[tex]\[ 1.4719 = e^{0.057 t} \][/tex]

To solve for [tex]\( t \)[/tex], we take the natural logarithm (ln) of both sides:

[tex]\[ \ln(1.4719) = \ln(e^{0.057 t}) \][/tex]

Since [tex]\( \ln(e^x) = x \)[/tex]:

[tex]\[ \ln(1.4719) = 0.057 t \][/tex]

Solving for [tex]\( t \)[/tex]:

[tex]\[ t = \frac{\ln(1.4719)}{0.057} \approx 6.8 \][/tex]

So, it will take approximately [tex]\( 6.8 \)[/tex] years for the investment to grow to \[tex]$13100. To summarize the answers: - \( f(0) = \$[/tex]8900.00 \)
- The amount in the account after 8 years is [tex]\( \$14041.98 \)[/tex]
- It will take approximately [tex]\( 6.8 \)[/tex] years for the investment to grow to [tex]\( \$13100 \)[/tex]