JAMB Mathematics 2023 Paper

Concept:Profit or loss percentage is always calculated based on the cost price.Explanation:Let the cost price be $C.P$.Given first selling price $S.P = ₦230$ and profit $15\%$.Use the profit formula: $\text{Profit \%} = \frac{S.P - C.P}{C.P} \times 100$Substitute the values:$15 = \frac{230 - C.P}{C.P} \times 100$Divide through by 100:$\frac{15}{100} = \frac{230 - C.P}{C.P}$Cross multiply:$15C.P = 100(230 - C.P)$$15C.P = 23000 - 100C.P$$115C.P = 23000$$C.P = \frac{23000}{115} = ₦200$The second selling price is $₦180$, which is lower than $C.P = ₦200$, so it is a loss.Use the loss formula: $\text{Loss \%} = \frac{C.P - S.P}{C.P} \times 100$$\text{Loss \%} = \frac{200 - 180}{200} \times 100$$\text{Loss \%} = \frac{20}{200} \times 100 = 10\%$Answer:It is a 10% loss.Correct option: B. 10% loss.