Question

A common blood test indicates the presence of a disease 95% of the time when the disease is actually present in an individual and indicates the absence of disease 95% of the time when the disease is actually absent in an individual. The disease occurs in 1% of the population. What is the probability than an individual has the disease if their blood test is positive? Round the answer to 2 decimal places and enter it into the box below.

Answer 1

Answer:0.161

Explanation:

GIven 99% population is disease free and 95 % times it detects correctly

1% population have disease and test detect 95% time correctly.

Probability that an individual has the disease and test show positive

`P\left [ (have\ disease)/(test\ show\ positive)\right ]`

P=
`(0.01* 0.95)/(0.99* 0.05+0.01* 0.05)`

P=
`(0.0095)/(0.059)`=0.161