An epidemiologist would like to measure the magnitude of the association between smoking and lung cancer in a town with approximately 400,000 residents who are 18 years of age and older. On the basis of a recent report from the National Health and Nutrition Examination Survey, the epidemiologist finds approximately 25% of the town's population are smokers and expects approximately 400 residents will develop lung cancer. 62.5% of the residents who have lung cancer are smokers.

A) Among the non-smoker residents what is the probability the residents do not have lung cancer.

B) Given the information, show that smoking habit and the development of lung cancer are not independent.