1. 有一堆police 其中在有inaccurate paper card 人中有60%的有inaccurate electric card ,在有inaccrate electric card 人中有75%的油inaccurate paper card.在所有人中有3%的人既有inaccurate paper card 又有inaccurate electric card .问在所有人中有百分之几是既有accurate paper card 又有accurate electric card.
大概是这个样子的。答案有97%，百分之九十的（记不太清了），68%，后面的也记不太清了。
答案：0。94
怎么做，是否最后DE问题有误？到底是BOTH INACCUATE 还是 BOTH ACCUATE？
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%,
For an inaccurate paper record, 60% chances that the electronic record is inaccurate.
x * 60% = 3% x = 5% (inaccurate paper record)
For an inaccurate electronic record, 75% chances that the paper record is inaccurate.
y * 75% = 3% y = 4% (inaccurate electronic record)
=> 2% inaccurate paper record, accurate electronic record
=> 1% inaccurate electronic record, accurate paper record
inaccurate paper record + inaccurate electronic record = 6%
ans:94%
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the explanation is from David thx to him ^^
2.the answers should be certain by each of the alternatives , but do not have to be identical
and for this problem , the two alternatives lead to the same answer , wxyz<0
3.I assume sth wrong with the problem , as far as I can remember , it is asking for the possibility as Bush is not selected as President ...anyway , to your statement
my answer is 1/10+9/10*(1/8)*(1/7)
hAPpy New YEAr ^^
