JAMB Mathematics 2021 Paper

Concept:Simple interest is charged only on the original principal, so determine the interest for 4 months, add it to the borrowed amount, then subtract the repayment.Explanation:Principal borrowed $= \mathrm{N}10.00$.Monthly interest rate $= 2\%$.Time $= 4$ months.Interest, $I = \frac{10 \times 2 \times 4}{100} = 0.8$.So the total amount owed after 4 months is $10.00 + 0.80 = \mathrm{N}10.80$.He repays $\mathrm{N}8.00$, so the balance is $10.80 - 8.00 = \mathrm{N}2.80$.Answer:He still owes $\mathrm{N}2.80$, which is option C.