The problem is "Twelve percent of the job applicants for a large company have recently smoked marijuana. The company gives all applicants a drug test. The test is not perfect. The test has a...

The problem is "Twelve percent of the job applicants for a large company have recently smoked marijuana. The company gives all applicants a drug test. The test is not perfect. The test has a sensitivity of 98%- meaning that 98% of those who have recently smoked marijuana will test positive, the other 2% will test negative. The test has a specificity of 96%- meaning that if someone has not recently smoked marijuana, the test will correctly yield a negative test result 96% of the time."

M = applicant has recently smoke marijuana
C= applicant has not recently smoked marijuana (clean)
X = positive test (test indicates that the person has not recently smoked marijuana recently)
N= negative test (test indicates that the person has not recently smoke marijuana)

a. What proportion of those who test positive have not recently smoked marijuana?

b. What proportion of those who pass the drug test really shouldn’t have?