select all the pairs of ratios that form a proportion pick two

1/6, 4/20
7/9, 28/36
14/18, 21/27
30, 6/18

2. which pair of ratios does not form a proportion pick one

3/5, 24/40
30/10, 15/5
9/14, 3/4
7/12, 14/24

3.two shirts cost 12.50 how much will it cost to buy five of the shirts

6.25
31.25
25.00 this one
30.00

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)