The times 12 athletes took to run 400 m are summarised in the table below.
| Athlete | A | B | C | D | E | F | G | H | A | I | J | K |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Time (s) | 45.2 | 46.9 | 46.1 | 46.2 | 45.4 | 45.1 | 47.8 | 45.4 | 45.5 | 46.1 | 46.4 | 45.7 |
Find the mean time taken.
Find the standard deviation for these times.
Find the median, upper and lower quartiles of these data.
4 exam-style questions on Edexcel A Level Maths 2.4 Variance and Standard Deviation. Each one has a worked solution and a mark scheme showing where the marks go.