# A person is selected at random from a population that has the following characteristics

A person is selected at random from a population that has the following characteristics:

65% of the people are men; the others are women

12% of the men are smokers

7% of the women are smokers


Find the chance that the selected person is a non-smoker, given that the person is a man.

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What have you tried? conditional probability? – Ehsan M. Kermani Apr 19 '13 at 17:51

You know that the person is a men and the chance the he is smoking is 12%. Assuming that smokers and non-smokers form a partition of men, $p(smoker)+p(non-smoker)=1.$ Substitute $p(smoker)$ by it's value, $0.12, p(non-smoker)=1-0.12=0.88=88$%