Probability of Emphysema in a Population - Calculation and Analysis

[sinni8]

check the answers please~

Ive done the following questions but not sure about my answers because i have different answers with my friend.. so please tell me whether its correct or wrong.. thank you! Question 2. In a region, 20% of the adult population are smokers,
0:9% are smokers with emphysema, and 0:2% are non-smokers with emphysema.
(a) What is the probability that a person, selected at random, has emphysema?
0.9% * 20% + 0.2% * 80% = 9/1000 * 1/5 + 2/1000 * 4/5 = 17/5000
(b) Given that the selected person is a smoker, what is the probability that this
person has emphysema?
0.9% = 9/1000
(c) Given that the selected person is not a smoker, what is the probability that
this person has emphysema?
0.2% = 2/1000 = 1/500

 

[mathman]

Looks right to me.