R1000 is invested for 2 years at a compound interest rate of 7% p.a. Calculate the compound interest earned after 2 years.
Understand the Problem
The question asks to calculate the compound interest earned on an investment of R1000 over 2 years at an interest rate of 7% per annum. This will involve using the compound interest formula to find the total amount after 2 years and then subtracting the initial investment to find the interest earned.
Answer
R144.90
Answer for screen readers
R144.90
Steps to Solve
- Write down the compound interest formula
The formula for compound interest is:
$A = P(1 + \frac{r}{n})^{nt}$
Where: $A$ = the future value of the investment/loan, including interest $P$ = the principal investment amount (the initial deposit or loan amount) $r$ = the annual interest rate (as a decimal) $n$ = the number of times that interest iscompounded per year $t$ = the number of years the money is invested or borrowed for
- Identify the values for each variable
From the problem statement: $P = R1000$ $r = 7% = 0.07$ $n = 1$ (since the interest is compounded annually) $t = 2$ years
- Substitute the values into the formula
Substitute the values of $P$, $r$, $n$, and $t$ into the compound interest formula:
$A = 1000(1 + \frac{0.07}{1})^{(1)(2)}$
- Calculate the value of A
Simplify the equation:
$A = 1000(1 + 0.07)^2$ $A = 1000(1.07)^2$ $A = 1000(1.1449)$ $A = 1144.90$
So, the future value of the investment after 2 years is R1144.90.
- Calculate the compound interest earned
To find the compound interest earned, subtract the principal amount from the future value:
$Compound\ Interest = A - P$ $Compound\ Interest = 1144.90 - 1000$ $Compound\ Interest = 144.90$
Therefore, the compound interest earned is R144.90.
R144.90
More Information
The compound interest earned on R1000 invested for 2 years at an annual interest rate of 7%, compounded annually, is R144.90.
Tips
A common mistake is forgetting to convert the interest rate from a percentage to a decimal. Also, forgetting the order of operations (PEMDAS/BODMAS) can lead to calculation errors. Another mistake is finding the final amount but forgetting to subtract the principal to find the interest earned.
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