Question 1061648
Consider a population of 100,000 who get the test. Of those people, .5%, or 500 people actually have the disease, but 7% will test negative, so 465 out of those 500 will test positive. Of the 99,500 who don't have the disease, 2%, or 1990 will test positive. In total, 2,455 will test positive, of which 465 will actually have the disease. So the ratio of diseased to positive tests is 465/2455 , or 0.18941. This is the probability that someone who tested positive actually has the disease. ☺☺☺☺