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percentage problem..

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by ska7945 » Fri Aug 22, 2008 11:22 pm
For what percent of those tested for a certain infection was the test accurate; that is, positive for those who had the infection and negative for those who did not have the infection?
(1) Of those who tested positive for the infection, 1/8 did not have the infection.
(2) Of those tested for the infection, 90 percent tested negative.


oa E
let's beat GMAT.
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Source: — Data Sufficiency |
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by carefreeamit » Sun Aug 24, 2008 10:50 pm
Since the ratio of infected v/s non infected is not known you can not find the final ratio.
option E.
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Yeah E is correct!

by kshankker » Thu Aug 28, 2008 2:31 am
Yeah answer will be E...
Stat.1 -tells u only no. of positive infection tested. No details about (Full )no.of tested members.

stat. 2 - tellu only % of negative infected members......

So A,D,B- ruled out. C ...wen u combine it - information insufficient so ruled out.....Hence E is the ans.


If iam wrong pls correct me.
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Re: percentage problem..

by stern » Thu Aug 28, 2008 12:18 pm
ska7945 wrote:For what percent of those tested for a certain infection was the test accurate; that is, positive for those who had the infection and negative for those who did not have the infection?
(1) Of those who tested positive for the infection, 1/8 did not have the infection.
(2) Of those tested for the infection, 90 percent tested negative.


oa E
E. Both of them combined can also not give us how much % of those tested negative have inaacurate results.
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