Read charts and graphs in context, check a claim against the numbers, justify a decision, and answer "show that" questions by giving more accuracy than the target.
What you will learn
- Interpret a chart or graph in the context of the question
- Decide whether a claim is right and say why
- Justify a choice with a calculated statistic
- Show that a value rounds to a given answer
Interpret means in context
To interpret a chart or graph, say what it means in the situation, with the numbers.
- Not "the line goes up" but "the more hours of revision, the higher the test mark tends to be".
- Not "it is flat" but "she stopped for 20 minutes".
On a distance-time graph, a flat line means stopped, and a steeper line means faster. Speed = distance ÷ time; change minutes to hours for km/h.
The time stopped is the length of the flat part. 6 km in 20 minutes: 20 minutes is 1/3 of an hour, so the speed is 6 ÷ 1/3 = 18 km/h. A line sloping down means coming back towards the start.
A graph can compare two charges. A taxi charging £3 plus £1.50 a mile has fare y = 3 + 1.5x: plot (0, 3), (2, 6), (4, 9) and so on. Where two lines cross, the two firms charge the same; to one side of the crossing the lower line is cheaper.
The rest of this lesson and its 9 practice questions are locked.
In this lesson
- Interpret means in context
- Scatter graphs
- Criticise a claim
- Justify a decision
- Show that
- Try it: An easy one first
9 practice questions, marked as you go; about 30 minutes in all.
In this unit: Problem solving and proof
Reasoning and problem solving: multi-step money problems, angle chains with reasons, interpreting and justifying with statistics, algebraic proof, and mixed problems across topics.
- Number and money problems
- Angle reasoning with reasons
- Interpret, justify and show that
- Proof and show that
- Mixed exam problems