Assume that 5% of the population of San Mateo county is suffering from COVID-19. For the PCR test, if a person has СOVID-19 the probability that the test result is positive is 0.8. The probability to have the negative result of the test given person does not have a COVID 19 is 0.9. A random person gets tested for the COVID 19 and the result comes back positive. What is the probability that the person has СOVID 19? The person gets tested for the COVID 19 and result negative, find the probability that this person has COVID-19.