The mileages, to the nearest thousand miles, of 90 cars are summarised in the table below.
| Mileage (thousand miles) | 1–10 | 11–20 | 21–40 | 41–60 |
|---|---|---|---|---|
| Frequency | 12 | 24 | 36 | 18 |
A histogram is drawn to represent these data.
Show that the bar representing the class 21–40 is shorter than the bar representing the class 11–20, even though more cars lie in the class 21–40.
Estimate the number of these cars whose recorded mileage is at most 30 thousand miles.
244 exam-style questions on AQA A Level Maths 2.2 L: Data presentation and interpretation, covering 2.2.1 Single-variable data diagrams, 2.2.2 Scatter diagrams and correlation, 2.2.3 Central tendency, variation and standard deviation, 2.2.4 Outliers and cleaning data, and 2.2 L: Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.