Question

A test subject is randomly selected for a pregnancy test. What is the probability of getting a subject who is not pregnant, given that the test result is positive? Find the probability using the data table.
Positive Test Negative Test
Subject is pregnant. 78 7
Subject is not pregnant. 12 28


A. 0.10



B. 0.13



C. 0.19



D. 0.25

Answer 1

You're given that the test result is positive, so only look at the first column not pregnant = 12 total = 78+12 = 90 probability = 12/90 = 0.13333333. 

Hence, the ans would be B.

Answer 2

The correct answer is 
B) 0.13