A transport engineer investigated the effectiveness of two different asphalt surface treatments, Treatment A (a polymer-modified coating) and Treatment B (a standard micro-surfacing emulsion), in reducing the braking distance of vehicles on wet roads. A higher value indicates a greater reduction in braking distance (in metres), which represents a safer and more effective treatment.
Table 1 Reduction in braking distance (metres) for 8 test runs using Treatment A:
| Test run | Reduction in braking distance (m) |
|---|---|
| 1 | 4.8 |
| 2 | 6.2 |
| 3 | 3.5 |
| 4 | 7.1 |
| 5 | 5.0 |
| 6 | 4.4 |
| 7 | 8.3 |
| 8 | 5.5 |
The engineer found that the mean reduction in braking distance for Treatment B was 4.9 m.
Give one conclusion about the effectiveness of the two treatments using the mean values for both treatments. Explain your answer.
235 exam-style questions on AQA A Level Psychology Data handling and analysis. Each one has a worked solution and a mark scheme showing where the marks go.