b. A principal of \( \$ 750 \) becomes-a total of \( \$ 1320 \) in 8 years. What rate of interest was beir paid?

To find the rate of interest, we can use the formula for simple interest: \[ \text{Simple Interest} = \frac{\text{Principal} \times \text{Rate} \times \text{Time}}{100} \] Given: - Principal = $750 - Total amount after 8 years = $1320 - Time = 8 years We need to find the rate of interest. Let's denote the rate of interest as \( r \) (in %). The total amount after 8 years is the sum of the principal and the simple interest: \[ \text{Total Amount} = \text{Principal} + \text{Simple Interest} \] Substitute the given values: \[ 1320 = 750 + \frac{750 \times r \times 8}{100} \] Now, we can solve for \( r \) to find the rate of interest. Solve the equation by following steps: - step0: Solve for \(r\): \(1320=750+\frac{750r\times 8}{100}\) - step1: Reduce the fraction: \(1320=750+60r\) - step2: Swap the sides: \(750+60r=1320\) - step3: Move the constant to the right side: \(60r=1320-750\) - step4: Subtract the numbers: \(60r=570\) - step5: Divide both sides: \(\frac{60r}{60}=\frac{570}{60}\) - step6: Divide the numbers: \(r=\frac{19}{2}\) The rate of interest \( r \) is 9.5%.