A histogram is drawn to represent the CO emissions, x x\,x g/km, of 300 cars. The four classes and their frequencies are given in the table below.
| CO emission (g/km) | Frequency |
|---|---|
| 0.0≤x<0.20.0 \le x < 0.20.0≤x<0.2 | aaa |
| 0.2≤x<0.30.2 \le x < 0.30.2≤x<0.3 | bbb |
| 0.3≤x<0.50.3 \le x < 0.50.3≤x<0.5 | 76 |
| 0.5≤x<0.90.5 \le x < 0.90.5≤x<0.9 | 24 |
On the histogram, the bar representing 0.2≤x<0.3 0.2 \le x < 0.3\,0.2≤x<0.3 is three times as tall as the bar representing 0.0≤x<0.20.0 \le x < 0.20.0≤x<0.2.
Show that b=1.5ab = 1.5ab=1.5a.
Find the value of a a\,a and the value of bbb.
Estimate the proportion of these 300 cars with a CO emission of less than 0.25 g/km.
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.