Line Graphs — Prelims Strategy

Prelims Strategy

Read the two axes and identify whether the graph reports levels, period totals or cumulative values. When there are several lines, assign each a short label from the legend and compare them at the same horizontal coordinate. Do not compare one series in one year with another in a different year unless asked.

For greatest-growth questions, check whether growth means absolute increase, percentage increase or rate per year. Unequal time gaps require division by elapsed time. For percentage changes, use the starting value of that interval. If the vertical axis already shows percentages, distinguish percentage-point change from relative percentage change.

Treat a connecting segment as an interpolation only when the problem authorises that reading. Do not infer a cause or a future value from visual alignment alone. In review, create a short table of levels, differences and rates for the same dataset. This reveals how several apparently similar questions demand different answers and helps prevent automatic selection of the tallest point.