Suppose 5% of the population have a certain disease.

Suppose 5% of the population have a certain disease. A laboratory blood test gives a positive reading for 95% of people who have the disease and 10% positive reading of people who do not have the disease. What is the probability of testing positive?

a)0.0475

b)0.1425

c)0.95

d)0.60

i was given the answer b but do not know how to get the answer please help... this is a problem from my review sheet for my exam today at 1pm thanks!