Achemist needs 80 milliliters of a 50% solution but she only has 20% and 60% solutions available. calculate how many milliliters of each should be mixed to get the desired result. how many milliliters of the 20% solution should she use?

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)