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Mathematical sampling grade
(1) Judging from the meaning of the question,

What is the total number of students in this class? 10 0.25 = 40 people?

∴ The number of students who got an A in the course of Reading and Expression is?

40× (1-0.375-0.375-0.15-0.025) = 40× 0.075 = 3 people.

(2) People who set two 10 points are: x 1, x2,

3 people 9 points; y 1,y2,y3。

Two people were randomly selected from five games.

(x 1,x2),(y 1,y2),(y 1,y3),(y2,y3),(x 1,y 1),

(x 1,y2),(x 1,y3),(x2,y 1),(x2,y2)(x2,y3)

*** 10 cases.

The sum of their grades is 19.

(x 1,y 1),(x 1,y2),(x 1,y3),(x2,y 1),(x2,y2)(x2,y3)

The situation in no.6 middle school.

The probability of finding that the sum of two people's scores is 19 is 35.