Annuity Values
1. **Problem 1: Future Value of an Ordinary Annuity (Simple Annuity)**
Maria deposits 5,000 every month for 5 years at 6% annual interest compounded monthly. We need to find the future value (FV) of this annuity.
- The formula for the future value of an ordinary annuity is:
$$FV = P \times \frac{(1 + r)^n - 1}{r}$$
where:
- $P = 5000$ (monthly deposit)
- $r = \frac{0.06}{12} = 0.005$ (monthly interest rate)
- $n = 5 \times 12 = 60$ (total number of payments)
Calculate:
$$FV = 5000 \times \frac{(1 + 0.005)^{60} - 1}{0.005}$$
First, compute $(1 + 0.005)^{60}$:
$$ (1.005)^{60} \approx 1.34885 $$
Then:
$$FV = 5000 \times \frac{1.34885 - 1}{0.005} = 5000 \times \frac{0.34885}{0.005} = 5000 \times 69.77 = 348,850$$
**Final answer:**
$FV = 348,850$
2. **Problem 2: Present Value of a Deferred Annuity (General Annuity)**
A company promises to pay 50,000 every quarter for 10 years, with an interest rate of 10% compounded monthly. We are to find the present value (PV) of this annuity.
- Quarterly payment, so frequency of payment is 4/year.
- Monthly compounding means monthly rate $i_m = 0.10/12 = 0.0083333$.
- We need an effective quarterly rate $r$ over 3 months:
$$r = (1 + i_m)^3 - 1 = (1 + 0.0083333)^3 - 1$$
Calculate:
$$r = 1.0252 - 1 = 0.0252$$
- Number of quarters $n = 10 \times 4 = 40$
- Present value formula for ordinary annuity:
$$PV = P \times \frac{1 - (1 + r)^{-n}}{r}$$
Substitute:
$$PV = 50000 \times \frac{1 - (1 + 0.0252)^{-40}}{0.0252}$$
Calculate $(1 + 0.0252)^{-40}$:
$$ (1.0252)^{-40} = \frac{1}{(1.0252)^{40}} \approx \frac{1}{2.718} = 0.368$$
Then:
$$PV = 50000 \times \frac{1 - 0.368}{0.0252} = 50000 \times \frac{0.632}{0.0252} = 50000 \times 25.08 = 1,254,000$$
**Final answer:**
$PV = 1,254,000$