∴x=40-23-12=5(名),
故答案为:5,0.575;
(2)第一档市民5人,依次设为A、B、C、D、E,则随机抽出两人的所有结果列表如下:
A | B | C | D | E | |
A | B,A | C,A | D,A | E,A | |
B | A,B | C,B | D,B | E,B | |
C | A,C | B,C | D,C | E,C | |
D | A,D | B,D | C,D | E,D | |
E | A,E | B,E | C,E | D,E |
∴P(A)=
6 |
20 |
3 |
10 |
A | B | C | D | E | |
A | B,A | C,A | D,A | E,A | |
B | A,B | C,B | D,B | E,B | |
C | A,C | B,C | D,C | E,C | |
D | A,D | B,D | C,D | E,D | |
E | A,E | B,E | C,E | D,E |
6 |
20 |
3 |
10 |