The incidence of a deadly disease, among a certain population,
is 0.01%. Individuals, randomly selected from this population are
submitted to a test whose accuracy is 99% both ways. That is to
say, the proportion of positive results among people known to be
affected by the disease is 99%. Likewise, testing people that are
not suffering from the disease yields 99% negative results. The
test gives independent results when repeated. An individual test
positive.
a) What is the probability that...