1. **State the problem:** Paul wants to accumulate at least 55000 by depositing 2000 at the end of every month into a fund with 6.25% annual interest compounded monthly. We need to find how many deposits (n) are required and the time in years and months.
2. **Formula for future value of an ordinary annuity:**
$$FV = P \times \frac{(1 + r)^n - 1}{r}$$
where $P$ is the monthly deposit, $r$ is the monthly interest rate, and $n$ is the number of deposits.
3. **Identify values:**
- $FV = 55000$
- $P = 2000$
- Annual interest rate = 6.25% so monthly rate $r = \frac{6.25}{100 \times 12} = 0.0052083$
4. **Set up equation:**
$$55000 = 2000 \times \frac{(1 + 0.0052083)^n - 1}{0.0052083}$$
5. **Isolate the term with $n$:**
$$\frac{55000 \times 0.0052083}{2000} = (1.0052083)^n - 1$$
Calculate left side:
$$\frac{55000 \times 0.0052083}{2000} = 0.143229$$
6. **Add 1 to both sides:**
$$(1.0052083)^n = 1 + 0.143229 = 1.143229$$
7. **Take natural logarithm of both sides:**
$$\ln((1.0052083)^n) = \ln(1.143229)$$
$$n \ln(1.0052083) = 0.1337$$
8. **Solve for $n$:**
$$n = \frac{0.1337}{\ln(1.0052083)}$$
Calculate denominator:
$$\ln(1.0052083) = 0.005195$$
So,
$$n = \frac{0.1337}{0.005195} = 25.74$$
9. **Round up to next whole deposit:**
$$n = 26$$ deposits
10. **Convert deposits to time:**
Each deposit is monthly, so 26 months.
11. **Convert months to years and months:**
$$26 \text{ months} = 2 \text{ years and } 2 \text{ months}$$
**Final answers:**
- a. Number of deposits needed: 26
- b. Time to reach goal: 2 years and 2 months
Annuity Deposits 4C7E6E
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