JAMB Mathematics 2020 Paper

Concept:Simple interest is calculated on the original principal only. The interest earned is the difference between the final amount and the principal.Explanation:Let the principal be $P = \mathrm{N}1000$.The amount accumulated after 3 years is $\mathrm{N}1240$.So, the simple interest is:$I = 1240 - 1000 = \mathrm{N}240$.Time, $T = 3$ years.Using the formula:$$I = \frac{PRT}{100}$$Substitute the known values:$$240 = \frac{1000 \times R \times 3}{100}$$This simplifies to:$$240 = 30R$$Therefore:$$R = \frac{240}{30} = 8\%$$Answer:The simple interest rate is $8\%$ per annum.The correct option is B.