Two new screening tests for Alzheimer's Disease (AD) have been developed. One is fast, cheap, and non-invasive the other is more accurate with a sensitivity of 99% and a specificity of 99% but is invasive and has risks. Results of the tests were later compared to the results of a post-mortem microscopic examination of the brain, considered the gold-standard.

The accurate but risky test was administeredto all of those who had tested positive on the fast & easy test.

When we calculate thepositive predictive valueof the accurate but risky test as applied to all of those who had tested positive on the fast and easy test we get?