José takes out a loan of $9000 - HSC - SSCE Mathematics Standard - Question 13 - 2024 - Paper 1

To find the total interest paid, subtract the initial loan amount from the total amount repaid:

$\text{Total Interest} = \text{Total Amount Repaid} - \text{Loan Amount}$

Plugging in the numbers:

$\text{Total Interest} = \$14,400 - \$9,000 = \$5,400$

The simple interest can be calculated using the formula:

$I = P \times r \times t$

Where:

• I is the total interest
• P is the principal amount (the loan)
• r is the rate of interest per annum
• t is the time in years

Rearranging for r:

$r = \frac{I}{P \times t}$

Substituting the values:

$r = \frac{5400}{9000 \times 4} = \frac{5400}{36000} = 0.15$

Converting to a percentage:

$r \approx 0.15 \times 100\% = 15\%$