Two candidates are running for​ president: John Democrat and Joe Republican. A recent survey concluded that John Democrat had a probability of 0.44 to win the election. Two hundred people are interviewed at random about whom they would vote for. A random variable X is defined as the number of people who said they would vote for John Democrat. Required:
Find the expected value of the random variable

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)