Connect with a community that values knowledge and expertise on IDNLearn.com. Receive prompt and accurate responses to your questions from our community of knowledgeable professionals ready to assist you at any time.

Suppose that [tex]\$88,000[/tex] is invested at [tex]3 \frac{1}{2} \%[/tex] interest, compounded quarterly.

a) Find the function for the amount to which the investment grows after [tex]t[/tex] years.

b) Find the amount of money in the account at [tex]t = 0, 2, 7, [/tex] and [tex]10[/tex] years.

a) The function for the amount to which the investment grows after [tex]t[/tex] years is [tex]A(t) = \square[/tex] (Simplify your answer. Type an expression using [tex]t[/tex] as the variable.)


Sagot :

To solve this problem, let's use the formula for compound interest:

[tex]\[ A(t) = P \left(1 + \frac{r}{n}\right)^{nt} \][/tex]

where:
- [tex]\( A(t) \)[/tex] is the amount of money accumulated after [tex]\( t \)[/tex] years, including interest.
- [tex]\( P \)[/tex] is the principal amount (the initial amount of money).
- [tex]\( r \)[/tex] is the annual interest rate (decimal).
- [tex]\( n \)[/tex] is the number of times interest is compounded per year.
- [tex]\( t \)[/tex] is the number of years the money is invested for.

### a) Finding the function for the amount to which the investment grows after [tex]\( t \)[/tex] years:

Given:
- [tex]\( P = \$88,000 \)[/tex]
- [tex]\( r = 3.5\% = 0.035 \)[/tex]
- [tex]\( n = 4 \)[/tex] (since the interest is compounded quarterly)

Substitute [tex]\( P \)[/tex], [tex]\( r \)[/tex], and [tex]\( n \)[/tex] into the compound interest formula:

[tex]\[ A(t) = 88000 \left(1 + \frac{0.035}{4}\right)^{4t} \][/tex]

Simplify the expression inside the parentheses:

[tex]\[ A(t) = 88000 \left(1 + 0.00875\right)^{4t} \][/tex]

[tex]\[ A(t) = 88000 \left(1.00875\right)^{4t} \][/tex]

Thus, the function for the amount to which the investment grows after [tex]\( t \)[/tex] years is:

[tex]\[ A(t) = 88000 \cdot 1.00875^{4t} \][/tex]

### b) Finding the amount of money in the account at [tex]\( t = 0, 2, 7, 10 \)[/tex] years:

Now, we will calculate [tex]\( A(t) \)[/tex] for [tex]\( t = 0, 2, 7, 10 \)[/tex]:

1. When [tex]\( t = 0 \)[/tex]:

[tex]\[ A(0) = 88000 \cdot 1.00875^{4 \cdot 0} \][/tex]

[tex]\[ A(0) = 88000 \cdot 1 = 88000 \][/tex]

So, the amount at [tex]\( t = 0 \)[/tex] years is [tex]\( \$88,000 \)[/tex].

2. When [tex]\( t = 2 \)[/tex]:

[tex]\[ A(2) = 88000 \cdot 1.00875^{4 \cdot 2} \][/tex]

[tex]\[ A(2) = 88000 \cdot 1.00875^8 \approx 94351.9877376592 \][/tex]

So, the amount at [tex]\( t = 2 \)[/tex] years is approximately [tex]\( \$94,351.99 \)[/tex].

3. When [tex]\( t = 7 \)[/tex]:

[tex]\[ A(7) = 88000 \cdot 1.00875^{4 \cdot 7} \][/tex]

[tex]\[ A(7) = 88000 \cdot 1.00875^{28} \approx 112310.926152495 \][/tex]

So, the amount at [tex]\( t = 7 \)[/tex] years is approximately [tex]\( \$112,310.93 \)[/tex].

4. When [tex]\( t = 10 \)[/tex]:

[tex]\[ A(10) = 88000 \cdot 1.00875^{4 \cdot 10} \][/tex]

[tex]\[ A(10) = 88000 \cdot 1.00875^{40} \approx 124687.977737940 \][/tex]

So, the amount at [tex]\( t = 10 \)[/tex] years is approximately [tex]\( \$124,687.98 \)[/tex].

### Summary:
- The function for the amount to which the investment grows after [tex]\( t \)[/tex] years is:
[tex]\[ A(t) = 88000 \cdot 1.00875^{4t} \][/tex]
- The amounts in the account at different times are:
- [tex]\( A(0) = \$88,000 \)[/tex]
- [tex]\( A(2) \approx \$94,351.99 \)[/tex]
- [tex]\( A(7) \approx \$112,310.93 \)[/tex]
- [tex]\( A(10) \approx \$124,687.98 \)[/tex]
We are happy to have you as part of our community. Keep asking, answering, and sharing your insights. Together, we can create a valuable knowledge resource. IDNLearn.com has the solutions you’re looking for. Thanks for visiting, and see you next time for more reliable information.