At age 40, 1% of people can be expected to lose vision later in life. There is a test that can detect vision loss early, before it begins to happen. Of those who will end up losing vision later in life, the test will correctly diagnose this 80% of the time. In addition, those who do not end up losing vision later in life will have a 9.6% chance of getting diagnosed from this test. Someone at 40 goes to get an early test for vision loss and it comes back positive. What is the probability they will actually experience vision loss later in life?

ANSWER:

P(lose vision | test positive) = .078

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