How do 0.5 becomes a fraction i dont understand plz help

Standard deviation of 19,29,21,22,23

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)

Identify reflection rule on a coordinate plane that verifies that triangle a(-1,7), b(6,5), c(-2,2) and a’(-1,-7), b(6,-5), c’(-2,2) triangle are congruent when reflected over the x-axis