m= 1000-6-82-256-220=436,
n=436 1000=0.436,N=220 1000=0.220。
The histogram of frequency distribution is shown in the following figure:
(2) Let the number of people with 90 points or above in liberal arts mathematics in the city be X,
Then 100020000 = 656x, and x =13120;
(iii) Let four boys be represented as A 1, A2, A3, A4,
Three girls are represented as B 1 of B3 B2,
The basic events of recruiting 2 students from 7 students are:
(A 1,A2),(A 1,A3),(A 1,A4),(A 1,B 1),(A 1,B2),(A 1,B3)、
(A2,A3),(A2,A4),(A2,B 1),(A2,B2),(A2,B3),(A3,A4),
(A3,B 1),(A3,B2),(A3,B3),(A4,B 1),(A4,B2),(A4,B3),
(B 1, B2), (B 1, B3), (B2, B3), ***2 1 species.
We take "there are 1 girls in 2 people" as event A, and there are:
(A 1,B 1),(A 1,B2),(A 1,B3),(A2,B 1),(A2,B2),(A2,B3)、
(A3,B 1),(A3,B2),(A3,B3),(A4,B 1),(A4,B2),(A4,B3),
*** 12 species,
∴P(A)= 122 1=47.
So two out of seven people are admitted, and the probability that 1 happens to be a girl is 47.