WAEC 2024 · Paper 1 · Q10

A trader gave a change of ₦540.00 instead of ₦570.00 to a customer. Calculate the percentage error.

Worked solution (try it first)

The error is ₦570.00 − ₦540.00 = ₦30.00.
Divide by the correct change and multiply by 100: $\frac{30}{570} \times 100\% = \frac{100}{19}\%$ .
$100 \div 19 = 5$ remainder 5, so the percentage error is $5\frac{5}{19}\%$ , option A.