WAEC Mathematics 2014 Paper

Concept:The lower quartile marks the point below which $25\%$ of the data lies.The $60$th percentile marks the point below which $60\%$ of the data lies.So the two required groups do not overlap and their percentages can be added.Explanation:At most $18$ years means the data up to the lower quartile: $25\%$.Greater than $48$ years means the data above the $60$th percentile: $100\% - 60\% = 40\%$.Add the two percentages: $25\% + 40\% = 65\%$.Answer:$65\%$Correct option: C.