Question

An article in the New England Journal of Medicine, reported about a study of smokers in California and Hawaii. In one part of the report, the self-reported ethnicity and smoking levels per day were given. Of the people smoking at most ten cigarettes per day, there were 9,886 African Americans, 2,745 Native Hawaiians, 12,831 Latinos, 8,378 Japanese Americans, and 7,650 Whites. Of the people smoking 11 to 20 cigarettes per day, there were 6,514 African Americans, 3,062 Native Hawaiians, 4,932 Latinos, 10,680 Japanese Americans, and 9,877 Whites. Of the people smoking 21 to 30 cigarettes per day, there were 1,671 African Americans, 1,419 Native Hawaiians, 1,406 Latinos, 4,715 Japanese Americans, and 6,062 Whites. Of the people smoking at least 31 cigarettes per day, there were 759 African Americans, 788 Native Hawaiians, 800 Latinos, 2,305 Japanese Americans, and 3,970 Whites.

Suppose that one person from the study is randomly selected. Find the probability that person smoked 11 to 20 cigarettes per day. (Enter your probability as a fraction.)

Answer 1

Let x = Number of cigarettes per day

Smoking Data Table

x	African Americans	Native Hawaiians	Latinos	Japanese Americans	Whites	Total
	9886	2745	12831	8378	7650	41490
	6514	3062	4932	10680	9877	35065
	1671	1419	1406	4715	6062	15273
	759	788	800	2305	3970	8622
Total	18830	8014	19969	26078	27559	100450

Total number of people smoke 11 to 20 cigarettes per day = 35065

Total number of people smoking cigarettes = 100450

P(selecting one person who smoked 11 to 20 cigarettes per day = 35065/100450 = 7013/20090