Yes, correct, nicely done.

Answer explanation. PPV = true positive/(true positive+false positive). We knew for that test with would get 90/10,000 true positives and 990/10,000 false positive, 1080 total positives. Therefore 90/1080 are true positives= 8.3%.

Since we’ve done PPV, let’s do a negative predictive value for the same test.

Calculate the negative predictive value for a test with 90% specificity, 90% sensitivity, and 1% prevalence. (let’s do this one as fractions rather than calculating %!)