Question

Your friend is worried she might have caught the flu. This season, about 1 in every 100 people will catch it. As yet, she hasn’t shown any particular symptoms, nor any particular reason to think that she’s more likely to have caught it than anyone else. Nevertheless, she has a test which boasts high levels of accuracy. If you have the flu, the test will return a positive result 99% of the time. If you don’t have the flu, it will return a negative result 90% of the time. Letting ‘F’ stand for ‘She has the flu’, and ‘T’ stand for ‘The test returns positive’, what are the values of the following (rounded to the 4th decimal):

find probabilitiy of (T). show work

Answer 1

The above question is solved using the theorem on total probability and the P(T) = 0.1089