So the probability that the city's air quality category is moderately polluted in this month?P =
| 6 |
| 30 |
| 1 |
| 5 |
(2) From the bar chart, we know that there are 4 data with the color of air quality category purple, which are set as a, b, c and d, and there are 2 data with the color of air quality category maroon, which are set as e and f.
Set any 2 data from the above 6 data, and at least one of the data reflecting the color of the air quality category maroon is the event A.
Then, basic events are: (a, b), (a, c), (a, d), (b, c), (b, d), (c, d), (a, e), (a, f), (b, e), (b, f), (c, e), (c, f), (d, e), (d, f), (e, f) *** 15 possibilities,
A contains the basic events: (a, e), (a, f) , (b, e), (b, f), (c, e), (c, f), (d, e), (d, f), (e, f) 9 possibilities,
Therefore, the probability sought, P(A) =
| 9 |
| 15 |
| 3 |
| 5 |