The table shows the times taken by 40 students to complete a data-analysis task. One frequency is missing.
| Time, \(t\) (minutes) | Frequency | Class midpoint |
|---|
| \(0<t\leq10\) | 4 | 5 |
| \(10<t\leq20\) | 9 | 15 |
| \(20<t\leq30\) | \(x\) | 25 |
| \(30<t\leq50\) | 8 | 40 |
| \(50<t\leq70\) | 3 | 60 |
The estimated mean time is calculated from the grouped table. Which statement gives both the missing frequency and the estimated mean correctly?
Select one option.