In: Statistics and Probability
The table summarizes data on smoking status and perceived risk of smoking and is consistent with summary quantities obtained in a Gallup Poll conducted in November 2002. Assume that it is reasonable to consider these data as representative of the U.S. adult population.
Perceived Risk | ||||
Smoking Status | Very Harmful | Somewhat Harmful | Not Too Harmful | Not at All Harmful |
Current Smoker | 58 | 35 | 5 | 1 |
Former Smoker | 69 | 20 | 3 | 2 |
Never Smoked | 85 | 11 | 2 | 1 |
(a) What is the probability that a randomly selected U.S. adult
is a former smoker? (Give the answer to four decimals
places.)
(b) What is the probability that a randomly selected U.S. adult
views smoking as very harmful? (Give the answer to four decimals
places.)
(c) What is the probability that a randomly selected U.S. adult
views smoking as very harmful given that the selected individual is
a current smoker? (Give the answer to four decimals places.)
(d) What is the probability that a randomly selected U.S. adult
views smoking as very harmful given that the selected individual is
a former smoker? (Give the answer to four decimals places.)
(e) What is the probability that a randomly selected U.S. adult
views smoking as very harmful given that the selected individual
never smoked? (Give the answer to four decimals places.)
Total = 292
a) P(Former smoker) = 94/292 = 0.3219
b) P(very harmful) = 212/292 = 0.7260
c) P(very harmful | current smoker) = P(very harmful and current smoker)/P(current smoker)
= 58/99 = 0.5859
d) P(very harmful | former smoker) = P(very harmful and former smoker)/P(former smoker)
= 69/94 = 0.7340
e) P(very harmful | never smoked) = P(very harmful and never smoked)/P(never smoked)
= 85/99 = 0.8586