甲:0中概率 0.4*0.4*0.4 =0.064
1中概率 0.4*0.6*0.4*3=0.288
2中概率 0.4*0.6*0.6*3=0.432
3中概率 0.6*0.6*0.6 =0.216
乙:0中概率 0.3*0.3*0.3 =0.027
1中概率 0.7*0.3*0.3*3=0.189
2中概率 0.7*0.7*0.3*3=0.441
3中概率 0.7*0.7*0.7 =0.343
故两人投中相等的概率是:
0.064*0.027+0.288*0.189+0.432*0.441+0.216*0.343=0.001728+0.054432+0.190512+0.074088=
0.23076