(I) Let this classmate hear pop songs as events A and B on Monday and Tuesday respectively, and he hears pop music as event C, then A and B are independent of each other, and C=AB.

Judging from the meaning of the question, p (a) = p (b) =1550 = 310,

∴ P(C)=P(AB)=P(A)？ P(B)= 9 100。

A: The probability that this student listens to pop songs on Monday and Tuesday is 9 100...6.

(2) According to the meaning of the question, the probability of playing folk music in school one day is 10 50 = 1 5, ξ ~ b (5, 1 5).

∴ e ξ = 5×15 =1...12 points.