WAEC 2019 · Paper 1 · Q15

Bala sold an article for ₦6,900.00 and made a profit of $15\%$ . Calculate his percentage profit if he had sold it for ₦6,600.00.

Worked solution (try it first)

₦6,900 is $115\%$ of the cost, so the cost is $6900 \div 1.15 =$ ₦6,000.
Selling for ₦6,600 gives a profit of $6600 - 6000 =$ ₦600.
As a percentage of the cost: $\dfrac{600}{6000} \times 100\% = 10\%$ , option B.