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