WAEC Mathematics 2013 Paper

Concept:Percentage error measures the difference between the incorrect value and the actual value, expressed as a percentage of the actual value.Explanation:The actual change should have been N72.The incorrect change given was N68.Error = Actual value − Incorrect valueError = $72 - 68 = 4$Percentage error = $\frac{\text{Error}}{\text{Actual value}} \times 100$Percentage error = $\frac{4}{72} \times 100$Percentage error = $\frac{400}{72}$Percentage error = $\frac{50}{9} = 5\frac{5}{9}\%$Answer:Option B: $5\frac{5}{9}\%$