1.6
3.2
1.5
1.25
1.15
5. The probability of A is 60% and the probability of B is 50%, what is the most possible probability that neither A nor B would happen?
0.80
0.40
0.75
0.55
0.68
6. There are 1200 respondents to a poll, each favoring their preference for candidates A,B, and C. 54% favored A, 48% favored B, and 42% favored C, and there is 30% favored both A and B. whats the largest possible number of respondents favoring C, but not CB, nor CA?
25%
30%
28%
38%
40%
参考答案:
1.解:首先考虑总的可能性为,再考虑A在1,B在2,C在3的可能性分别为,中重复计算了三者交集,分别为AB在1,2,AC在1,3,BC在2,3,所需将三种情况加回,即,但考虑这三种加回的交集又重复计算了ABC在1,2,3的情况,所以应减去P33
2.解:在平面直角坐标系中,T
3.解:设总数为x,设incorrect paper record有y, incorrect electric record有z,则:
xy60%=3%x y=5%
xz75%=3%x z=4%
则,两者至少有一个错误的百分比为5%+4%-3%=6%,所正确答案为94%
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