fozzzy wrote:
isn't this question asking for 2 variables? I got the answer E
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Infection tests.jpg [ 122.08 KiB | Viewed 3621 times ]
I think this problem goes beyond 2 variables. You can use the overlapping sets table, as there can be 4 possibilities for patient to be infected/not-infected:
Tests are Positive & Accurate -> Patient is infected
Tests are Positive & Inaccurate -> Patient is NOT infected
Tests are Negative & Accurate -> Patient is NOT infected
Tests are Negative & Inaccurate -> Patient is infected
Our objective is to identify the value of cell marked in yellow (i.e. Accurate tests) hence find its ratio to TOTAL tests (i.e. % Accuracy)
(1) Of those who tested positive for the infection,1/8 did not have the infection.
INSUFFICIENT: Refer to the diagram, this gives no info to derive the value for yellow cell (i.e. Accurate tests)
(2) Of those tested for the infection, 90 percent tested negative.
INSUFFICIENT: Refer to the diagram, this gives no info to derive the value for yellow cell (i.e. Accurate tests)
Combining (1) & (2)
INSUFFICIENT: Even after combining the statements are INSUFFICIENT to derive the value for yellow cell (i.e. Accurate tests)
Hence Choice(E) is the answer. _________________
Thanks,
Prashant Ponde
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