please assist

Question

A new non-invasive screening test that is claimed to be able to identify patients with impaired glucose tolerance, based on a battery of questions related to health behaviors. As mentioned, the new test is given to 75 patients. Based on each patient's responses to the questions, they are classified as positive or negative for impaired glucose tolerance. Each patient also submits a blood sample which is used to determine each patient's glucose tolerance status.
Of those who tested positive on the screening test, 17 were found to have impaired glucose tolerance, and 13 were determined to not be impaired. Of those who tested negative on the screening test, 8 were found to have impaired glucose tolerance and 37 were determined to not be impaired. What is the false positive fraction of the screening test?

a. 0.26

b. 0.43

c. 0.17

d. None of the above.

Answer 1

A 'false positive fraction' or false positive rate is the proportion of non-carriers of the condition in question who will test positive.  The number of non-carriers in this circumstance is 50:  the 13 non-impaired who tested positive, plus the 37 non-impaired who tested negative.  (In other words, the false positives plus the true negatives).  The false positive fraction is then 13/50, or .26.