Two cuboid-shaped metal bars are the same size. they are 12.4cm long, 5.6cm wide and 2.5cm thick. one bar is iron with a density of 7.9g/cm3 and the other is copper with a density of 9.0g/cm3. what is the difference in there masses to the nearest gram?

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)