We can re-word this to make it easier. 1000 people take a test. 1 of them has a disease, and the test will probably return positive for that person. 999 of th

We can re-word this to make it easier. 1000 people take a test. 1 of them has a disease, and the test will probably return positive for that person. 999 of them do not have the disease, and the test will return positive for about 9 of them.