Probability question?

Question

Assume that 2% of the Brazilian population have dengue fever in 2008 and that a test correctly identifies the fever 95% of the time. Assume that a false positive occurs 5% of the time. If a person tests positive for the fever, what is the probability that the person actually has the fever?

Answer 1

The 2% is extraneous information.  Your question only relates to the probability of the positive result being correct.  The answer is contained in the question...  The test is correct 95% of the time so your probability is 95% or 95/100.