The times, t t\,t minutes, taken by 80 drivers to complete a journey are summarised in the table below.
| Time (minutes) | Frequency |
|---|---|
| 0<t≤100 < t \le 100<t≤10 | 6 |
| 10<t≤2010 < t \le 2010<t≤20 | 18 |
| 20<t≤3020 < t \le 3020<t≤30 | 30 |
| 30<t≤5030 < t \le 5030<t≤50 | 20 |
| 50<t≤8050 < t \le 8050<t≤80 | 6 |
Estimate the mean time taken.
Estimate the standard deviation of the times.
105 exam-style questions on WJEC A Level Maths 2.2 Data presentation and interpretation, covering 2.2.1 Data presentation and interpretation, 2.2.2 Data presentation and interpretation, 2.2.3 Data presentation and interpretation, 2.2.4 Data presentation and interpretation, 2.2.5 Data presentation and interpretation, 2.2.6 Data presentation and interpretation, 2.2.7 Data presentation and interpretation, 2.2.8 Data presentation and interpretation, and 2.2 Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.