We are given three financial problems to solve: (8) A man invests Tk. 10,000 and withdraws Tk. 1,500 at the end of each year for 7 years. The money is invested at 4% per annum. We need to find the amount left after 7 years. (9) Mr. Karim can purchase a machine by paying Tk. 40,000 in cash or by 8 equal yearly installments paid at the beginning of each year. The interest rate is 12%. We need to find the amount of each installment. (10) You borrowed Tk. 42,000 at 12% to be repaid over 8 years with equal installment payments at the end of each year. We must prepare an amortization schedule for a lender providing an 8% return. This seems to be a typo: should be for a lender requiring a 12% return, which is the initial interest rate. I will create the schedule using the correct 12% interest rate and loan amount of 42,000.
Applied MathematicsFinancial MathematicsCompound InterestAnnuitiesAmortization SchedulePresent ValueFuture Value
2025/4/14
1. Problem Description
We are given three financial problems to solve:
(8) A man invests Tk. 10,000 and withdraws Tk. 1,500 at the end of each year for 7 years. The money is invested at 4% per annum. We need to find the amount left after 7 years.
(9) Mr. Karim can purchase a machine by paying Tk. 40,000 in cash or by 8 equal yearly installments paid at the beginning of each year. The interest rate is 12%. We need to find the amount of each installment.
(10) You borrowed Tk. 42,000 at 12% to be repaid over 8 years with equal installment payments at the end of each year. We must prepare an amortization schedule for a lender providing an 8% return. This seems to be a typo: should be for a lender requiring a 12% return, which is the initial interest rate. I will create the schedule using the correct 12% interest rate and loan amount of 42,
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2. Solution Steps
Problem 8:
We need to calculate the future value of the initial investment and subtract the future value of the series of withdrawals.
Let be the initial investment, be the annual withdrawal, be the interest rate, and be the number of years.
The future value of the initial investment after 7 years is:
The future value of the series of withdrawals is:
The amount left after 7 years is:
Problem 9:
This is an annuity due problem.
Let be the present value of the machine, be the number of installments, and be the interest rate. Let be the amount of each installment.
The present value of an annuity due is given by:
Problem 10:
We are given a loan of Tk. 42,000 at 12% to be repaid over 8 years. We need to create an amortization schedule.
Let be the loan amount, be the interest rate, and be the number of years.
First, we calculate the annual payment A using the annuity formula:
Now, we construct the amortization schedule.
| Year | Beginning Balance | Payment | Interest | Principal | Ending Balance |
|------|-------------------|---------|----------|-----------|----------------|
| 0 | 42000.00 | | | | 42000.00 |
| 1 | 42000.00 | 8454.47 | 5040.00 | 3414.47 | 38585.53 |
| 2 | 38585.53 | 8454.47 | 4630.26 | 3824.21 | 34761.32 |
| 3 | 34761.32 | 8454.47 | 4171.36 | 4283.11 | 30478.21 |
| 4 | 30478.21 | 8454.47 | 3657.39 | 4797.08 | 25681.13 |
| 5 | 25681.13 | 8454.47 | 3081.74 | 5372.73 | 20308.40 |
| 6 | 20308.40 | 8454.47 | 2437.01 | 6017.46 | 14290.94 |
| 7 | 14290.94 | 8454.47 | 1714.91 | 6739.56 | 7551.38 |
| 8 | 7551.38 | 8454.47 | 906.17 | 7548.30 | 3.08 |
3. Final Answer
Problem 8: Tk. 1319.97
Problem 9: Tk. 7188.34
Problem 10: See the amortization schedule above.