A teacher records the time, in minutes, taken by 60 students to complete a logic puzzle.
| Time (t t\,t mins) | Frequency |
|---|---|
| 0<t≤50 < t \leq 50<t≤5 | 4 |
| 5<t≤105 < t \leq 105<t≤10 | 11 |
| 10<t≤1510 < t \leq 1510<t≤15 | 24 |
| 15<t≤2015 < t \leq 2015<t≤20 | 13 |
| 20<t≤3020 < t \leq 3020<t≤30 | 8 |
Estimate the mean time taken to complete the puzzle. Give your answer correct to 1 decimal place.
Explain why your answer to part (a) is an estimate.
