How do you do this problem 2/5+4a=-6/5 what does a = to?

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)

Is the response to the survey question "did you smoke in the last week question mark "response to the survey question "did you smoke in the last week? " a discrete random variable, a continuous random variable, or not a random variable?

Write each improper fraction as a mixed number. 9/4. 8/3. 23/6. 11/2. 17/5. 15/8. 33/10. 29/12.