Single Line Graphs — Revision Notes

⚡ 30-Second Revision

Revision checked 17 October 2026.

Read coordinates and grid spaces accurately.
Rate needs elapsed time.
A missing point is unknown.
Interpolation needs a stated model.
Signed changes sum to final minus initial.

2-Minute Revision

For tank volumes 120, 90, 90 and 150 at 08:00, 09:00, 10:00 and 12:00, changes are −30, 0 and +60 litres. The last rate is +30 litres per hour, and the overall net change is +30 litres. Equal volumes do not prove zero inflow. Under linear interpolation only, 10:30 gives 105 litres. Keep level, change and rate separate.

5-Minute Revision

Original drill: A storage series is 50 at hour 0, 70 at hour 2 and 40 at hour 3. The first average rate is +10 units per hour; the second is −30. The greatest recorded level is 70, while the greatest absolute rate occurs during the decline. Net change is −10, matching +20 − 30. If the first segment is explicitly linear, hour 1 has value 60. Without that assumption, the hour-1 value is not measured. Explain each answer with its unit and assumption.

Vyyuha Quick Recall

POINT: Position; Ordered time; Interval length; Numerical unit; Test endpoint change.