Final answer:
The future value of an annuity formula is used to determine the amount in the IRA at retirement after making monthly deposits and the amount that should be deposited semiannually to reach a goal of $5,000 for a vacation, as well as interest earned in both scenarios.
Step-by-step explanation:
To determine how much you will have in the IRA when you retire at age 65 after starting at age 33 with a monthly deposit of $60 and an annual interest rate of 5.5% compounded monthly, we need to use the future value of an annuity formula:
FV = P × [( (1 + r)n - 1 ) / r ]
where:
FV = future value of the annuity (amount in the IRA at retirement)
P = monthly payment ($60)
r = monthly interest rate (5.5% annual rate / 12 months = 0.0045833)
n = total number of payments (32 years × 12 months/year = 384 payments)
Therefore, the future value of the annuity is:
FV = 60 × [[(1 + 0.0045833)384 - 1] / 0.0045833]
We calculate the future value and then subtract the total deposits from it to find the total interest earned by retirement.
For the second question, to have $5,000 in 5 years with deposits made semiannually at an interest rate of 4.5% compounded semiannually, we use the future value of an annuity formula again but solve for the periodic payment P.
The formula rearranges to:
P = FV / [( (1 + r)n - 1 ) / r ]
where: FV = $5,000, r = semiannual interest rate (4.5% annual rate / 2), and n = number of deposits (5 years × 2 deposits/year).
After finding P, we calculate total deposits by multiplying P by n, and then we subtract total deposits from $5,000 to determine how much comes from interest.