Question

Math

Posted 2 months ago

```
A zoo has separate habitats for its three types of bears: brown, black, and grizzly bears. Each habitat offers three areas for the bears to spend their time: an outdoor area, an indoor area, and a pool.
Gisele is the zookeeper who cares for the brown bear. She takes a random sample of 10 moments each day for a week and records which area the brown bear is at each of those moments. Bryan and Adele use a similar strategy and obtain separate samples of 70 observations for the black and grizzly bears, respectively. Here are their results:
\begin{tabular}{lrrrr}
Bear & Outdoor & Indoor & Pool & Total \\
\hline Brown & 23 & 27 & 20 & 70 \\
Black & 15 & 18 & 37 & 70 \\
Grizzly & 32 & 12 & 26 & 70 \\
Total & 70 & 57 & 83 & 210
\end{tabular}
They want to perform a $\chi^{2}$ test for homogeneity to judge if the bears are spending their time differently in their habitats.
What is the expected count for the cell corresponding to the grizzly bear being by the pool?
You may round your answer to the nearest hundredth.
Expected:
```

Sign in to unlock the answer

Answer from Sia

Posted 2 months ago

Solution by Steps

step 1

Calculate the expected count for the grizzly bears by the pool using the formula for expected frequency in a chi-square test: $E_{ij} = \frac{(row\ total) \times (column\ total)}{grand\ total}$

step 2

Identify the row total for grizzly bears and the column total for the pool: $row\ total = 70$, $column\ total = 83$, $grand\ total = 210$

step 3

Substitute the identified totals into the formula: $E_{grizzly,pool} = \frac{(70) \times (83)}{210}$

step 4

Perform the calculation: $E_{grizzly,pool} = \frac{(70) \times (83)}{210} = \frac{5810}{210}$

step 5

Simplify the fraction to find the expected count: $E_{grizzly,pool} = 27.666666666666666666666666666666666666666666666666666666666666666...$

step 6

Round the expected count to the nearest hundredth: $E_{grizzly,pool} \approx 27.67$

Answer

The expected count for the cell corresponding to grizzly bears being by the pool is approximately 27.67.

Key Concept

Expected Frequency in a Chi-Square Test

Explanation

The expected frequency for a cell in a chi-square test is calculated by multiplying the row total by the column total and dividing by the grand total. This provides the expected count if there is no difference in the distribution across the categories.

Not the question you are looking for? Ask here!

Enter question by text

Enter question by image

Upgrade to Asksia Pro

Join a AskSia's Pro Plan, and get 24/7 AI tutoring for your reviews, assignments, quizzes and exam preps.

Unlimited chat query usages

Strong algorithms that better know you

Early access to new release features

Study Other Question