【备考每日练】GRE数学题之错误百分比辨析
- 2014年09月12日10:38 来源:小站整理
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从2014年9月开始,小站教育将推出每日一题系列项目,借此帮助各位考生更好地备考GRE考试,我们也将在第一时间内提供题目的答案与解析。希望大家积极参加练习,努力提高自己的能力!小伙伴们一起来做题吧!来看看今天为大家带来的GRE数学练习题目。
In an insurance company, each policy has a paper record and an electric record. For those policies having incorrect paper record, 60% also having incorrect electric record; For policies having incorrect electric record, 75% also having incorrect paper record. 3% of all policies have both incorrect paper and incorrect electric records. If we randomly pick out one policy,what’s the probability that the one having both correct paper and correct electric records?
(A) 0.80
(B) 0.94
(C) 0.75
(D) 0.88
(E) 0.92
正确答案:B
解析:设总数为x,设incorrect paper record有y, incorrect electric record有z,则x·y·60%=3%·x y=5%,x·z·75%=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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