6. A test for a virus gives a positive result 98% of the time ir a person has the virus, but it also gives a false positive result 1% of the time if the person does not have the virus. Random testing is carried out on the population. (a) Calculate the probability that a person who tests positive for the virus has the virus when the proportion of people in the pulation with the virus is: K 1 in 1000 [2] (11) 1 in 10 [2] Kb Comment on the usefulness of the two different situations. [2] (c) If it is equally likely that someone who kesis positive for the virus has the virus as it is that they do not have the virus, what is the proportion of people in the population with the virus [4]
