Solution: The frequency between (1) 30 and 35 is 0.04×5=0.2,

Because there are eight volunteers aged 30 to 35,

∴n= = 40；

The frequency between 20 and 30 is1~ (0.01+0.04+0.02+0.01) × 5 = 0.6.

∴N 1 =0.6×40=24

(2) According to (1), there are 12 volunteers aged 20-25 and 8 volunteers aged 30-35.

Let "there are at most 1 English teachers among the selected candidates" as event A, then

P(A)= × =

(3) According to the meaning of the question, there are 4 female teachers and 2 male teachers;

x = 0. 1.2

P(X=0)=，

P(X= 1)=，

p(X = 2)= 1

So the distribution list is

The average value is.