The table below shows the distribution of the number of hours two groups of volunteers, Group P and Group Q, spent on a community project last month. Each group consists of 20 volunteers.
| Hours Spent | Group P Frequency | Group Q Frequency |
|---|---|---|
| 10 | 2 | 7 |
| 15 | 6 | 5 |
| 20 | 7 | 4 |
| 25 | 5 | 4 |
What is the positive difference between the mean number of hours spent by Group P and Group Q?
1.0 hours
1.5 hours
2.0 hours
2.5 hours
