Answered>Order 289

1) Suppose that 1% of all people have a particular disease. A test for the disease is 99% accurate. This means that a person who has the disease has a 99% chance of testing positive for the disease, while a person who doesn’t have the disease has a 99% chance of testing negative for the disease.

If a person tests positive for the disease, what is the chance (rounded to the nearest hundredth) that he or she actually has the disease?

I thought the answer is 99% but it seems to be wrong… Please help me understand where I went wrong.

Possible Answers:

0.99