解法1:
“a”批准: 0.7
“a”不批准“b”批准“c”批准: 0.3*0.7*0.7= 0.147
“a”不批准“b”批准“c”不批准“d”批准:0.3*0.7*0.3*0.7= 0.0441
0.7+0.147+0.0441 = 0.8911
解法2:
“a”不批准“b”不批准: 0.3*0.3=0.09
“a”不批准“b”批准“c”不批准“d”不批准=0.3*0.7*0.3*0.3=0.0189
1-0.09-0.0189=0.8911
解法1:
“a”批准: 0.7
“a”不批准“b”批准“c”批准: 0.3*0.7*0.7= 0.147
“a”不批准“b”批准“c”不批准“d”批准:0.3*0.7*0.3*0.7= 0.0441
0.7+0.147+0.0441 = 0.8911
解法2:
“a”不批准“b”不批准: 0.3*0.3=0.09
“a”不批准“b”批准“c”不批准“d”不批准=0.3*0.7*0.3*0.3=0.0189
1-0.09-0.0189=0.8911