Question

A certain disease is present in 1 in 200 of the population.In a mass screening program quick test for the disease is used, but the test is not totally reliable. For someone who does have the disease there is a probability of 0.9 that the test will prove positive, whereas for someone who does not have the disease there is a probability of 0.02 that the test will prove positive.

i.one person is selected at random and tested.
a.Draw a tree diagram, which illustrates one application of test.
b.Find the probability that the person has the disease and the test is positive.
c. Find the probability that the test is negative.
d.Given that the test is positive,find the probability that the person has the disease.
Only d

Answer 1

ii.People for who, the test proves a positive are recalled and re-tested.Find the probability that a person has the disease if the second test also proves positive.

Answer 2

its confusing i wish to help but its confusing to me