A leisure centre logs every class it runs, with the day and how many people came. Some classes ran more than once on the same day. The log is a DataFrame called log:
| class | day | attendees |
|---|---|---|
| Yoga | Mon | 12 |
| Spin | Mon | 18 |
| Yoga | Tue | 9 |
| Pilates | Mon | 7 |
| Spin | Wed | 15 |
| Yoga | Mon | 16 |
| Spin | Mon | 14 |
| Pilates | Wed | 11 |
| Yoga | Wed | 10 |
| Spin | Mon | 19 |
| Yoga | Tue | 13 |
The manager builds a grid of typical turnouts and then asks how Spin is doing across the week:
What does the last line print? Give your answer rounded to 2 decimal places.