(2) If m=2 in (1), the number of people with scores above 120 = 80;

(3)∫ Number of students in the first group =4.

The number of people with achievements in the sixth group is two. Let's assume that the scores of four people in the first group are A, B, C and D respectively.

In the sixth group, the scores of two people are X and Y respectively, and the basic events that can be formed by the scores of any one of them are: (a, b), (a, c), (a, d), (a, x), (a, y), (b, c), (b, d), (b). There are eight basic events (a, x), (a, y), (b, x), (b, y), (c, x), (c, y), (d, x), (d, y) * *, and the difference of their grades is greater than 50.

So the probability that their grade difference is greater than 50 is: p =.