91影视

$\text{An article in the New England Journal of Medicine, reported about a study of smokers in California and Hawaii. In one part of the report, the self-reported ethnicity and smoking levels per day were given. Of the people smoking at most ten cigarettes per day, there were}9,886\text{African Americans,}2,745\text{Native Hawaiians,}12,831\text{Latinos,}8,378\text{Japanese Americans, and}7,650\text{Whites. Of the people smoking}11to20\text{cigarettes per day, there were}6,514\text{African Americans,}3,062\text{Native Hawaiians,}4,932\text{Latinos,}10,680\text{Japanese Americans, and}9,877\text{Whites. Of the people smoking}21to30\text{cigarettes per day, there were}1,671\text{African Americans,}1,419\text{Native Hawaiians,}1,406\text{Latinos,}4,715\text{Japanese Americans, and}6,062\text{Whites. Of the people smoking at least}31\text{cigarettes per day, there were}759\text{African Americans,}788\text{Native Hawaiians,}800\text{Latinos,}2,305\text{Japanese Americans, and}3,970\text{Whites}$

We know, according to the table,

Step 3 : Final answer

Here,

We need to select a person who is Japanese American out of those who smokes $21to30$21 to 30 cigarettes.

Since, there is $4715$person who is Japanese American and smokes $21to30$cigarettes. So, by using normal method of probability in which to get the probability we divide no. of favorable outcomes by total no. of events. So, probability is $4715$divided by $100450.$

$P(thatpersonisJapaneseAmericanANDsmokes21to30cigarettesperday)=\frac{4715}{100450}.$

Now probability that the person smokes $21to30$cigarettes is $15273$divided by $100450$this is simply because that there is $15273$people who smokes $21to30$cigarettes and total no. of person is data-custom-editor="chemistry" $100450$.

$P(Thatapersonwillsmoke21to30cigarettesperday)=\frac{15273}{100450}$

Now, by using the method of conditional probability we obtain our answer in which we have use the formula

$$\begin{gathered} P(A鈭�B)=\frac{P(A鈭�B)}{P\left(B\right)} \\ =\frac{\frac{4713}{10323}}{\frac{13233}{100420}} \\ =\frac{4715}{15273} \\ =0.3087 \end{gathered}$$

"We need to select one person who is Japanese American given that he smokes $21to30$cigarettes per day" means we need to select a person who is Japanese American out of those who smokes $21to30$cigarettes.

The required solution is$0.3087.$