A1.35.c
Identify possible associations and trends in categorical data.
Example Problems
Three office buildings surveyed a random sample of employees about their recycling habits. Here are the results:
They want to perform a χ² test of homogeneity on these results.
What is the expected count for the cell corresponding to Building B employees who never recycle?
Round your answer to the nearest hundredth.
| Building | Always | Sometimes | Never | Total |
|---|---|---|---|---|
| Building A | 50 | 20 | 10 | 80 |
| Building B | 40 | 30 | 10 | 80 |
| Building C | 30 | 25 | 15 | 70 |
| Total | 120 | 75 | 35 | 230 |
They want to perform a χ² test of homogeneity on these results.
What is the expected count for the cell corresponding to Building B employees who never recycle?
Round your answer to the nearest hundredth.
Kira surveyed three neighborhoods about pet ownership. Each neighborhood provided a random sample of households. Here are the results:
They want to perform a χ² test of homogeneity on these results.
What is the expected count for the cell corresponding to households in Neighborhood C that own a cat?
| Neighborhood | Dog | Cat | Neither | Total |
|---|---|---|---|---|
| Neighborhood A | 35 | 22 | 13 | 70 |
| Neighborhood B | 28 | 30 | 12 | 70 |
| Neighborhood C | 24 | 18 | 18 | 60 |
| Total | 87 | 70 | 43 | 200 |
They want to perform a χ² test of homogeneity on these results.
What is the expected count for the cell corresponding to households in Neighborhood C that own a cat?
Librarians at three branches randomly sampled patrons and asked which types of books they had read in the past month. Here are the results:
They want to perform a χ² test of homogeneity on these results.
What is the expected count for the cell corresponding to East branch patrons who read Fiction?
Round your answer to the nearest hundredth.
| Library branch | Fiction | Nonfiction | Both | Total |
|---|---|---|---|---|
| North branch | 40 | 25 | 15 | 80 |
| East branch | 30 | 20 | 10 | 60 |
| South branch | 35 | 30 | 15 | 80 |
| Total | 105 | 75 | 40 | 220 |
They want to perform a χ² test of homogeneity on these results.
What is the expected count for the cell corresponding to East branch patrons who read Fiction?
Round your answer to the nearest hundredth.

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