Victoria had [tex]$\$[/tex]200[tex]$ in her account at the end of one year. At the beginning of each subsequent year, she deposits $[/tex]\[tex]$15$[/tex] into the account and earns [tex]$2\%$[/tex] interest on the new balance, compounded annually. Which recursive formula represents the total amount of money in Victoria's account at the end of the [tex]$n$[/tex]th year?

A. [tex]a_n = 1.02\left(a_{n-1} + 15\right) ; a_1 = 215[/tex]

B. [tex]a_n = 15 + 1.02a_{n-1} ; a_1 = 215[/tex]

C. [tex]a_n = 1.02\left(a_{n-1} + 15\right) ; a_1 = 200[/tex]

D. [tex]a_n = 15 + 1.02a_{n-1} ; a_1 = 200[/tex]



Answer :

Let's analyze the situation to determine which recursive formula correctly represents the total amount of money in Victoria's account at the end of the [tex]\( n \)[/tex]-th year.

1. Initial Amount: Victoria has \[tex]$200 in her account at the end of the first year. 2. Deposit and Interest: - At the beginning of each subsequent year, she deposits \$[/tex]15 into the account.
- Then, she earns 2% interest on the new balance, compounded annually.

To construct the recursive formula, let's first understand the account balance changes step-by-step:

- At the beginning of the [tex]\( n \)[/tex]-th year, she adds \[tex]$15 to the previous year's balance. - Then, she earns 2% interest on this new balance. Let \( a_{n-1} \) represent the total amount at the end of the \((n-1)\)-th year. At the beginning of the \( n \)-th year, the balance, after adding the deposit but before interest, is \( a_{n-1} + 15 \). Then, she earns 2% interest on this new total. The recursive formula to express this is: \[ a_n = 1.02(a_{n-1} + 15) \] Now let's determine the initial condition: - At the end of the first year, after adding the deposit and interest, she has \$[/tex]215.

Thus, the initial condition is [tex]\( a_1 = 215 \)[/tex].

Therefore, the correct recursive formula is:
[tex]\[ a_n = 1.02(a_{n-1} + 15) \quad \text{with} \quad a_1 = 215 \][/tex]

From the provided options, this corresponds to:
[tex]\[ a_n = 1.02(a_{n-1} + 15); \quad a_1 = 215 \][/tex]

So, the correct answer is:
[tex]\[ a_n = 1.02(a_{n-1} + 15); \quad a_1 = 215 \][/tex]