Final answer:
To achieve her savings goal of $20,000 for college expenses with a bank account compounding quarterly at 7% interest, Elena must calculate the required quarterly payment using the annuity formula, substituting the known values to solve for the payment amount.
Step-by-step explanation:
Elena wants to save $20,000 for her son's college expenses with a bank account that offers a 7% interest rate compounded quarterly. Since she plans to make contributions at the end of each quarter, we can calculate the necessary payment using the future value of an annuity formula:
FV = PMT * [((1 + r/n)^(nt) - 1) / (r/n)]
Where:
- FV = Future value of the annuity (Elena's goal of $20,000)
- PMT = The payment per period (quarter) that Elena needs to find
- r = Annual interest rate in decimal (0.07 for 7%)
- n = Number of times the interest is compounded per year (4 for quarterly)
- t = The number of years the money is invested or the payments are made (16 years)
Rearranging the formula to solve for PMT, we get:
PMT = FV / [((1 + r/n)^(nt) - 1) / (r/n)]
Substituting the values:
PMT = $20,000 / [((1 + 0.07/4)^(4*16) - 1) / (0.07/4)]
Calculating the above expression will give us the quarterly payment Elena needs to make to achieve her savings goal.