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A Data Sufficiency Problem

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by olym2008 » Wed Nov 19, 2008 2:57 am
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, did not have the infection.
(2) Of those tested for the infection, 90 percent tested negative.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

Could you tell me why the answer is E ? :roll:
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Source: — Data Sufficiency |

by jimmiejaz » Wed Nov 19, 2008 5:06 am
I think that the statement 1 is incomplete. please post the complete statement.
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by 4meonly » Thu Nov 20, 2008 8:25 am
E is because there is no information about those whose got negative results - were these results correct or not. Until this, you dont know the percentage of test mistakes
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