Reducing Interest Loans
1. **State the problem:**
Ashika borrows 180000 at 4.8% per annum compounded monthly, repaid monthly over 20 years. We use the formula $$PV = PMT \times \frac{1 - (1 + i)^{-n}}{i}$$ to find monthly repayment and balances.
2. **Find values of $i$ and $n$: **
- Annual interest rate = 4.8% = 0.048
- Monthly interest rate $$i = \frac{0.048}{12} = 0.004$$
- Number of monthly payments $$n = 20 \times 12 = 240$$
3. **Calculate monthly repayment $PMT$: **
Rearranging formula:
$$PMT = PV \times \frac{i}{1 - (1 + i)^{-n}}$$
Substitute values:
$$PMT = 180000 \times \frac{0.004}{1 - (1 + 0.004)^{-240}}$$
Calculate denominator:
$$(1 + 0.004)^{-240} = (1.004)^{-240} \approx 0.392838$$
So denominator:
$$1 - 0.392838 = 0.607162$$
Thus:
$$PMT = 180000 \times \frac{0.004}{0.607162} = 180000 \times 0.006587 = 1185.66$$
4. **Total amount paid over 20 years: **
$$\text{Total} = PMT \times n = 1185.66 \times 240 = 284558.40$$
5. **Total interest paid: **
$$\text{Interest} = \text{Total} - PV = 284558.40 - 180000 = 104558.40$$
6. **Outstanding balance after 200th payment: **
Use formula for outstanding balance after $n$ payments:
$$\text{Balance} = PMT \times \frac{1 - (1 + i)^{-(N-n)}}{i}$$
Where $N=240$, $n=200$:
$$\text{Balance} = 1185.66 \times \frac{1 - (1.004)^{-(240-200)}}{0.004}$$
Calculate exponent:
$$(1.004)^{-40} \approx 0.852143$$
Calculate numerator:
$$1 - 0.852143 = 0.147857$$
Calculate balance:
$$1185.66 \times \frac{0.147857}{0.004} = 1185.66 \times 36.964 = 43810.44$$
**Final answers:**
- $i = 0.004$
- $n = 240$
- $PMT = 1185.66$
- Total paid = 284558.40
- Interest paid = 104558.40
- Outstanding balance after 200th payment = 43810.44