Hazy weather affects people.

Analysis: (1) The sample data of a certain market are 32, 33, 34, 46, 62 and 69 respectively.

The sample data of city B are 34, 38, 5 1, 6 1, 63, 7 1 respectively.

. x A = 32+33+34+46+62+696 = 46，。 x B = 34+38+5 1+63+7 16 = 53；

Because. X A

So the air quality in a city is better.

(2) According to the stem and leaf chart, the air quality level of a city is Grade I in three days and Grade II in three days.

Three-day data of air quality level I are a 1, a2, a3, and three-day data of air quality level II are b 1, b2, b3.

Then all the cases of choosing two of the six days are: a 1a2, a 1a3, a 1b 1, a 1b2, a 1b3, a2b 1, and a2b/.

That is, the total number of basic events is15;

I still remember "One day the air quality level was Grade 1" as event A,

Then the basic events contained in event A are: a 1b 1, a 1b2, a 1b3, a2b 1, a2b2, a2b3, a3b 1, a3b2, a3b3,

That is, the number of events contained in event A is 9; ?

So p (a) = 9 15 = 35,

In other words, the probability that one day the air quality level is 1 level is 35.