A random sample of 300 men who suffered from lung disease was classified as (1) smoker versus non-smoker and (2) use of coffee on a typical day. The results are: Use of Coffee Smoker Non-Smoker Total
1 or fewer cups/day 42 15 57
2 or more cups/day 222 21 243
Total 264 36 300
Suppose we randomly select a man who suffers from lung disease.
Define the events:
S = individual is a smoker
C = individual drinks two or more cups of coffee per day.
(a) Find P(S).
A. 42 / 264 = 0.1591
B. 264 / 300 = 0.8800
C. 57 / 300 = 0.1900
D. 42 / 300 = 0.1400
E. None of the above.
(b) What is P(S and C)?
A. 42 / 264 = 0.1591
B. 264 / 300 = 0.8800
C. 57 / 300 = 0.1900
D. 222 / 300 = 0.7400
E. None of the above.
(c) Find P(S | C).
A. 222 / 243 = 0.9136
B. 222 / 264 = 0.8409
C. 42 / 57 = 0.7368
D. 264 / 243 = 1.0864
E. None of the above.
(d) Are S and C independent events?
A. No because P(C) ≠ P(S).
B. No because P(S | C) ≠ P(S).
C. Yes because smoking and coffee use are not related.
D. Yes because coffee use and lung disease are not related.
E. None of the above