How many ways are there to choose a half dozen donuts from 10 varieties a)If there are no two donuts of the same variety. b)If there are at least two varieties. c)If there must be at least one but no more than 4 glazed.

Anew test for ra is being developed. the test is administered to 750 patients with ra and 750 without ra. for the sake of the question, assume the prevalence of ra in this population is 50%. of the 750 patients with ra, 575 have a positive result. of the 750 patients without ra, 150 have a positive result. what is the positive predictive value of the new test? a575/(575+150) b. 600/(600+ 150) c. 575/(575+125) d. 600/(600+ 125)