# In 1912 the luxury liner Titanic struck an iceberg and sank. Some passengers got off the ship in lifeboats, but many died. The two-way table gives information about adult passengers who survived and who died, by class of travel. Check the conditions for performing a chisquare test for association. begin{array}{l|c|c|c|c} & text { First } & text { Second } & text { Third } & text { Total } hline text { Survived } & 197 & 94 & 151 & 442 hline text { Died } & 122 & 167 & 476 & 765 hline text { Total } & 319 & 261 & 627 & 1207 end{array}

Question
Two-way tables
In 1912 the luxury liner Titanic struck an iceberg and sank. Some passengers got off the ship in lifeboats, but many died. The two-way table gives information about adult passengers who survived and who died, by class of travel. Check the conditions for performing a chisquare test for association.
$$\begin{array}{l|c|c|c|c} & \text { First } & \text { Second } & \text { Third } & \text { Total } \\ \hline \text { Survived } & 197 & 94 & 151 & 442 \\ \hline \text { Died } & 122 & 167 & 476 & 765 \\ \hline \text { Total } & 319 & 261 & 627 & 1207 \\ \end{array}$$

2021-01-31
Given: $$\begin{array}{l|c|c|c|c} & \text { First } & \text { Second } & \text { Third } & \text { Total } \\ \hline \text { Survived } & 197 & 94 & 151 & 442 \\ \hline \text { Died } & 122 & 167 & 476 & 765 \\ \hline \text { Total } & 319 & 261 & 627 & 1207 \\ \end{array}$$
The null hypothesis states that there is no difference in the distribution of the categorical variable for exch of the populations/treatments. The alternative hypothesis states that there is a difference.
$$H_0$$: The distribution of candy chosen is the same for each survey type.
$$H_a$$: The distribution of candy chosen is not the same for each survey type.
The expected frequencies are the product of the column and row total,divided by the table total.
$$E_{11}=\frac{r_1 \times c_1}{n}=\frac{442 \times 319}{1207} \approx 116.82$$
$$E_{12}=\frac{r_1 \times c_2}{n}=\frac{442 \times 261}{1207} \approx 95.58$$
$$E_{13}=\frac{r_1 \times c_3}{n}=\frac{442 \times 627}{1207} \approx 229.61$$
$$E_{21}=\frac{r_2 \times c_1}{n}=\frac{765 \times 319}{1207} \approx 202.18$$
$$E_{22}=\frac{r_2 \times c_2}{n}=\frac{765 \times 261}{1207} \approx 165.42$$
$$E_{23}=\frac{r_2 \times c_3}{n}=\frac{765 \times 627}{1207} \approx 397.39$$ Conditions
The conditions for performing a chi-square test of homogeneity /independence are: Random, Independent: (10%), Large counts.
Random: Not satisfied, because the passengers of the titanic were not randomly selected..
Independent: Satisfied, because the 1207 people are less than 10% of all people (since there are more than 12070 people).
Large counts: Satisfied, because all expected counts are at least 5.
Since the random condition is not satisfied, it is not appropriate to carry out a test of homogeneity ‘independence.
All conditions are satisfied.

### Relevant Questions

The Titanic struck an iceberg and sank on its first voyage across the Atlantic in 1912. Some passengers got off the ship in lifeboats, but many died. The two-way table gives information about adult passengers who survived and who died, by class of travel.
$$\begin{array}{c|c} & First & Second & Third \\ \hline Yes & 197 & 94 & 151\\ \hline No & 122 & 167 & 476\\ \end{array}$$
Suppose we randomly select one of the adult passengers who rode on the Titanic. Given that the person selected was in first class, what's the probability that he or she survived?
In 1912 the Titanic struck an iceberg and sank on its first voyage. Some passengers got off the ship in lifeboats, but many died. The following two-way table gives information about adult passengers who survived and who died, by class of travel.
$$\begin{array} {lc} & \text{Class} \ \text {Survived } & \begin{array}{c|c|c|c} & \text { First } & \text { Second } & \text { Third } \\ \hline \text { Yes } & 197 & 94 & 151 \\ \hline \text { No } & 122 & 167 & 476 \end{array}\ \end{array}$$
Suppose we randomly select one of the adult passengers who rode on the Titanic. Define event D as getting a person who died and event F as getting a passenger in first class. Find P(not a passenger in first class or survived).
A survey of 4826 randomly selected young adults (aged 19 to 25 ) asked, "What do you think are the chances you will have much more than a middle-class income at age 30? The two-way table summarizes the responses.
$$\begin{array} {c|cc|c} & \text { Female } & \text { Male } & \text { Total } \\ \hline \text { Almost no chance } & 96 & 98 & 194 \\ \hline \text { Some chance but probably not } & 426 & 286 & 712 \\ \hline \text { A 50-50 chance } & 696 & 720 & 1416 \\ \hline \text { A good chance } & 663 & 758 & 1421 \\ \hline \text { Almost certain } & 486 & 597 & 1083 \\ \hline \text { Total } & 2367 & 2459 & 4826 \end{array}$$
Choose a survey respondent at random. Define events G: a good chance, M: male, and N: almost no chance. Given that the chosen student didn't say "almost no chance," what's the probability that this person is female? Write your answer as a probability statement using correct symbols for the events.
The following is a two-way table showing preferences for an award (A, B, C) by gender for the students sampled in survey. Test whether the data indicate there is some association between gender and preferred award.
$$\begin{array}{|c|c|c|}\hline &\text{A}&\text{B}&\text{C}&\text{Total}\\\hline \text{Female} &20&76&73&169\\ \hline \text{Male}&11&73&109&193 \\ \hline \text{Total}&31&149&182&360 \\ \hline \end{array}\\$$
Chi-square statistic=?
p-value=?
Conclusion: (reject or do not reject $$H_0$$)
Does the test indicate an association between gender and preferred award? (yes/no)
The Pew Research Center asked a random sample of 2024 adult cellphone owners from the United States their age and which type of cell phone they own: iPhone, Android, or other (including non-smartphones). The two-way table summarizes the data.
$$\begin{array}{c|ccc|c} & 18-34 & 35-54 & 55+ & \text { Total } \\ \hline \text { iPhone } & 169 & 171 & 127 & 467 \\ \text { Androod } & 214 & 189 & 100 & 503 \\ \text { Other } & 134 & 277 & 643 & 1054 \\ \hline \text { Total } & 517 & 637 & 870 & 2024 \end{array}$$
Suppose we select one of the survey respondents at random. What's the probability that: The person is not age 18 to 34 and does not own an iPhone?
This two-way table shows the results of asking students if they prefer to have gym class in the morning or the afternoon A.How many students participate in the survey B. How many students in grade 8 prefer to have gym in the morning C. How many grade 10 students participated in the survey D. How many students prefer To have gym in the afternoon
$$\begin{array}{|c|c|c|}\hline&\text{morning}&\text{afternoon}&\text{total}\\\hline\text{grade 6} &15 & 8 & 23\\ \hline\text{grade 8}& 18 & 21&39\\\hline\text{grade 10}& 12 & 26&38\\ \hline \text{total}&45&55&100 \\ \hline \end{array}$$
A random sample of 1200 U.S. college students was asked, "What is your perception of your own body? Do you feel that you are overweight, underweight, or about right?" The two-way table summarizes the data on perceived body image by gender.
$$\begin{array}{c|c} & Female\ \ \ \ \ \ Male & Total \\ \hline About\ right & 560\ \ \ \ \ \ \ \ \ \ 295 & 855\\ \hline Overweight & 163\ \ \ \ \ \ \ \ \ \ 72 & 235 \\ \hline Underweight & 37\ \ \ \ \ \ \ \ \ \ \ \ 73 & 110 \\ \hline Total & 760\ \ \ \ \ \ \ \ \ \ 440 & 1200 \end{array}$$
What proportion of the sample is female?
1950 randomly selected adults were asked if they think they are financially better off than their parents. The following table gives the two-way classification of the responses based on the education levels of the persons included in the survey and whether they are financially better off, the same as, or worse off than their parents
$$\begin{array}{|c|c|c|}\hline &\text{Less Than High School}&\text{High School}&\text{More Than High School}\\\hline \text{Better off} &140&440&430\\ \hline \text{Same as}&60&230&110\\ \hline \text{Worse off}&180&280&80\\ \hline\end{array}\\$$
Suppose one adult is selected at random from these 1950 adults. Find the following probablity.
Round your answer to three decimal places.
$$P(\text{more than high school or worse off})=?$$
The following table gives a two-way classification of all basketball players at a state university who began their college careers between 2004 and 2008, based on gender and whether or not they graduated.
$$\begin{array}{|c|c|c|}\hline &\text{Graduated}&\text{Did not Graduate}\\\hline \text{Male} &129&51\\ \hline \text{Female}&134&36 \\ \hline \end{array}\\$$
If one of these players is selected at random, find the following probability.
Round your answer to four decimal places.
$$P(\text{graduated or male})=$$ Enter your answer in accordance to the question statement
In this exercise , a two-way table is shown for two groups , 1 and 2 , and two possible outcomes , A nad B $$\begin{array}{|c|c|c|}\hline &\text{Outcome A}&\text{Outcome B}&\text{Total}\\\hline \text{Group 1} &30&20&50\\ \hline \text{Group 2}&40&110&150\\ \hline \text{Total}&70&130&200\\ \hline \end{array}\\$$
a) What proportion of all cases had Outcome A?
b) What proportion of all cases are in Group 1?
c) What proportion of cases in group 1 had Outcome B?
d) What proportion of cases who had Outcome A were in group 2?
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