Another solution

2003-01-01 16:12:58

29.An insurance company has a paper record and an electronic record for every claim. For an inaccurate paper record, 60% chances that the electronic record is inaccurate. For an inaccurate electronic record, 75% chances that the paper record is inaccurate. 3% of all the claims are inaccurate both in paper record and in electronic record. Pick one claim randomly, what are the chances that it is both accurate in paper record and in electronic record?
A.97% B.94% C.68% D.65% E.35%
【确定】B 94%,
思路：考条件概率，p(B|A)=60% p(A|B)=75%.p(AB)=3%, 1-p(A+B)=94%

I think the correct answer is A. Here is the approach.

Let IP be the number of inaccurate paper record, IE the number of inaccurate electronic record, CPP the % of accurate paper record, CEP the % of accurate electronic record, and NC the number of claims. Accordingly,
60%IP = 3%NC => IP/NC = 5%
75%IE = 3%NC => IE/NC = 4%
So % of inaccurate in either paper record or electronic record is 5% + 4% - 3% = 6%
Since
CPP = 1 - 5% = 95%
CEP = 1 - 4% = 96%
% of both accurate in paper record and in electronic record is (95% + 96%) - (100% - 6%) = 97%

Sorry I can't type Chinese. Hope it works.

Happy New Year to you all!

Phoenix

>>打印此页<<

>>关闭窗口<<