Question 51 of 480
A man wishes to keep his money in a savings deposit at 25% compound interest so that after three years he can buy a car for N150,000. How much does he need to deposit?
- A. N112,000.50
- B. N96,000.00
- C. N85,714.28
- D. N76,800.00
Correct Answer:
D
Explanation
To determine how much money the man needs to deposit today in order to have N150,000 after three years at a compound interest rate of 25%, we can use the formula for compound interest. The formula is:
\[
A = P(1 + r)^n
\]
Where:
- \( A \) is the amount of money accumulated after n years, including interest.
- \( P \) is the principal amount (the initial amount of money).
- \( r \) is the annual interest rate (decimal).
- \( n \) is the number of years the money is invested or borrowed.
### Step-by-Step Solution
1. **Identify the variables**:
- We know \( A = 150,000 \) (the amount he wants after 3 years).
- The interest rate \( r = 25\% = 0.25 \).
- The time period \( n = 3 \) years.
2. **Rearranging the formula**:
We need to find \( P \), so we rearrange the formula to solve for \( P \):
\[
P = \frac{A}{(1 + r)^n}
\]
3. **Substituting the values**:
Now we substitute the known values into the rearranged formula:
\[
P = \frac{150,000}{(1 + 0.25)^3}
\]
4. **Calculating \( (1 + r)^n \)**:
First, calculate \( (1 + 0.25)^3 \):
\[
(1 + 0.25) = 1.25
\]
\[
(1.25)^3 = 1.25 \times 1.25 \times 1.25
\]
- First, calculate \( 1.25 \times 1.25 = 1.5625 \).
- Then, multiply \( 1.5625 \times 1.25 = 1.953125 \).
5. **Calculating \( P \)**:
Now substitute back into the equation for \( P \):
\[
P = \frac{150,000}{1.953125}
\]
Performing the division:
\[
P \approx 76,800.00
\]
### Conclusion
Thus, the amount the man needs to deposit today is approximately **N76,800.00**.
### Explanation of Options
- **Option A: N112,000.50** - This amount is too high. If he deposited this amount, he would end up with much more than N150,000 after three years.
- **Option B: N96,000.00** - This is also too high. Similar to option A, this would yield more than N150,000.
- **Option C: N85,714.28** - This amount is still higher than necessary. It would also result in more than N150,000 after three years.
- **Option D: N76,800.00** - This is the correct answer, as calculated above.
### Revision Summary
- Use the compound interest formula \( A = P(1 + r)^n \) to find the principal.
- Rearrange the formula to solve for \( P \): \( P = \frac{A}{(1 + r)^n} \).
- Calculate \( (1 + r)^n \) carefully to avoid errors.
- Substitute values accurately to find the required deposit amount.
This thorough understanding of the compound interest formula and careful calculations will help in similar problems in the future.