The fractional variance of a and b is s2 A = 15 [(98? 1 10)2+( 106? 1 10)2+( 109? 1 10)2+( 1 18? 1 10)2+( 1 19? 1 10) 2] = 3065，s2 B = 15 [( 102？ 1 10)2+( 102? 1 10)2+( 1 1 1? 1 10)2+( 1 14? 1 10)2+( 12 1? 1 10)2]=2665

From X A =。 X B, s2 A > S2 B, we can know 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 we choose B.

(2) Two of Party B's five training achievements are randomly selected, and there are 10 basic events, namely:

{ 1 1 1, 1 14},{ 1 1 1, 12 1},{ 1 14, 12 1}, { 102, 102},{ 102, 1 1 1},{ 102, 1 14},{ 102, 12 1},{ 102, 1 1 1},{ 102, 1 14},{ 102, 12 1},

There are four basic events with a score of 12 1, so the probability of choosing a score of 12 1 is p = 4 10 = 25.