The average scores of a and b are,

.

The variances of the results of A and B are respectively

,

From,, we can see that the average level of A and B is the same, the variance of B is small, and B is more stable than A, so B is chosen.

(2) Randomly select two of the five training results of B. * * There are 10 basic events, that is, four of them have a score of 12 1, so the probability of choosing 12 1 is.