4. A saliva-based test that is easy-to-administer, scalable, sensitive and specific to SARS-CoV-2, the virus that causes COVID-19. The test produces rapid results, at costs significantly below alternatives such as nasal swabs. Suppose the COVID 19 infection rate in U.S. is 24% and the detection rate of the saliva-based test 97% among the people who got infected by COVID-19 but it gives 10% of false positive (Test shows positive even though the persons were not infected by COVID-19). If we use this test for 10,000 randomly selected individual, how many peoples actually has COVID-19 among the persons who got positive results from the saliva-based test. A=Infected by Covid-19 A' = No Covid-19 Infection B= Positive test results B'=Negative test results Bayes Formula