The table below gives information about the time taken for 20 people to run 5 km.
| Time (minutes) | Frequency |
|---|---|
| 15<t≤2015 < t \leq 2015<t≤20 | 3 |
| 20<t≤2520 < t \leq 2520<t≤25 | 6 |
| 25<t≤3025 < t \leq 3025<t≤30 | 7 |
| 30<t≤4030 < t \leq 4030<t≤40 | 4 |
Find the class interval that contains the median.
Work out an estimate for the mean time.