The average value of b = 7× 4+8× 3+9× 2+10×10 = 8;

The median of b is 8+82 = 8; The mode of b is 7;

Variance of B =4 (7? 8)2+2(9? 8)2+( 10? 8)2 10= 1;

Excellent rate B = 3+2+ 1 10 = 60%.

The average median variance was 8.881.680% and 8.871.060%. From the point of view of mean and median, there are 8 questions with equal scores.

For the most part, group A has 8 questions and group B has 7 questions, and group A is better than group B;

In terms of variance, A's performance gap is large, while B's is relatively stable;

Judging from the excellent and good rate, A is better than B.