The daily maximum temperature, in ∘ ^\circ\,∘C, was recorded for 21 days in a city.
| 18 | 22 | 31 | 15 | 19 | 27 | 24 |
| 21 | 29 | 30 | 26 | 17 | 25 | 20 |
| 16 | 23 | 28 | 34 | 32 | 22 | 18 |
Draw an ordered stem and leaf diagram to show this information. You must include a key.
One of the days is selected at random. Find the probability that the maximum temperature was less than 20∘ 20^\circ\,20∘C.
