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You are conducting a Goodness of Fit Chi-Squared hypothesis test [tex]\((\alpha=0.05)\)[/tex] for the claim that all 5 categories are equally likely to be selected. Complete the table.

\begin{tabular}{|c|l|l|l|}
\hline
Category & \begin{tabular}{c}
Observed \\
Frequency
\end{tabular} & \begin{tabular}{c}
Expected \\
Frequency
\end{tabular} & [tex]\((O-E)^2/E\)[/tex] \\
\hline
A & 18 & [tex]$\square$[/tex] & [tex]$\square$[/tex] \\
\hline
B & 9 & [tex]$\square$[/tex] & [tex]$\square$[/tex] \\
\hline
C & 15 & [tex]$\square$[/tex] & [tex]$\square$[/tex] \\
\hline
D & 13 & [tex]$\square$[/tex] & [tex]$\square$[/tex] \\
\hline
E & 10 & [tex]$\square$[/tex] & [tex]$\square$[/tex] \\
\hline
\end{tabular}

Round Expected values accurate to exactly 2 decimal places. Retain unrounded numbers for future calculations.
Round the [tex]\(\left((O-E)^2 / E\right)\)[/tex] values to 3 decimals.

1. What is the chi-square test-statistic for this data? (Round answer to 3 decimal places, and remember to use the unrounded Pearson residuals in your calculations.)

[tex]\[ x^2 = \square \][/tex]

2. What are the degrees of freedom for this test?

[tex]\[ d.f. = \square \][/tex]

3. What is the [tex]\(p\)[/tex]-value for this sample? (Round answer to 3 decimal places.)

[tex]\[ p\text{-value} = \square \][/tex]

4. The [tex]\(p\)[/tex]-value is...

[tex]\(\square\)[/tex] less than (or equal to) [tex]\(\alpha\)[/tex]

[tex]\(\square\)[/tex] greater than [tex]\(\alpha\)[/tex]

5. This test statistic leads to a decision to...

[tex]\(\square\)[/tex] reject the null

[tex]\(\square\)[/tex] fail to reject the null

6. As such, the final conclusion is that...

[tex]\(\square\)[/tex] There is sufficient evidence to warrant rejection of the claim that all 5 categories are equally likely to be selected.

[tex]\(\square\)[/tex] There is not sufficient evidence to warrant rejection of the claim that all 5 categories are equally likely to be selected.


Sagot :

Let's go through the steps to complete the table and answer the questions in the most detailed manner:

### Expected Frequencies

First, we calculate the total observed frequency:
[tex]\[ 18 + 9 + 15 + 13 + 10 = 65 \][/tex]
Since there are 5 categories, the expected frequency for each category is:
[tex]\[ \frac{65}{5} = 13.00 \][/tex]

So, the expected frequencies for categories A, B, C, D, and E are:
[tex]\[ \text{Expected Frequency} = 13.00 \][/tex]

### (O-E)^2 / E Calculation
Now, we calculate [tex]\((O-E)^2 / E\)[/tex] for each category.

#### Category A:
[tex]\[ O = 18, \, E = 13.00 \][/tex]
[tex]\[ \left(\frac{(18 - 13)^2}{13}\right) = \left(\frac{25}{13}\right) = 1.923 \][/tex]

#### Category B:
[tex]\[ O = 9, \, E = 13.00 \][/tex]
[tex]\[ \left(\frac{(9 - 13)^2}{13}\right) = \left(\frac{16}{13}\right) = 1.231 \][/tex]

#### Category C:
[tex]\[ O = 15, \, E = 13.00 \][/tex]
[tex]\[ \left(\frac{(15 - 13)^2}{13}\right) = \left(\frac{4}{13}\right) = 0.308 \][/tex]

#### Category D:
[tex]\[ O = 13, \, E = 13.00 \][/tex]
[tex]\[ \left(\frac{(13 - 13)^2}{13}\right) = \left(\frac{0}{13}\right) = 0.000 \][/tex]

#### Category E:
[tex]\[ O = 10, \, E = 13.00 \][/tex]
[tex]\[ \left(\frac{(10 - 13)^2}{13}\right) = \left(\frac{9}{13}\right) = 0.692 \][/tex]

### Completing the Table
[tex]\[ \begin{array}{|c|l|l|l|} \hline \text{Category} & \text{Observed Frequency} & \text{Expected Frequency} & \left(\frac{(O-E)^2}{E}\right)\\ \hline \text{A} & 18 & 13.00 & 1.923 \\ \hline \text{B} & 9 & 13.00 & 1.231 \\ \hline \text{C} & 15 & 13.00 & 0.308 \\ \hline \text{D} & 13 & 13.00 & 0.000 \\ \hline \text{E} & 10 & 13.00 & 0.692 \\ \hline \end{array} \][/tex]

### Chi-Square Test Statistic
To find the chi-square test statistic, sum all the [tex]\(\left(\frac{(O-E)^2}{E}\right)\)[/tex] values:
[tex]\[ \chi^2 = 1.923 + 1.231 + 0.308 + 0.000 + 0.692 = 4.154 \][/tex]

### Degrees of Freedom
The degrees of freedom (df) in a chi-square test is calculated as:
[tex]\[ \text{df} = \text{number of categories} - 1 = 5 - 1 = 4 \][/tex]

### p-Value
A chi-square test with the test statistic value of 4.154 and degrees of freedom 4 yields a p-value of:
[tex]\[ p = 0.386 \][/tex]

### Decision Based on p-Value
Comparing the p-value to the significance level [tex]\(\alpha = 0.05\)[/tex]:
[tex]\[ p \text{ (0.386) is greater than } \alpha \text{ (0.05)} \][/tex]

### Conclusion
Since the p-value is greater than [tex]\(\alpha\)[/tex], we:
[tex]\[ \text{fail to reject the null} \][/tex]

This leads to the final conclusion:
[tex]\[ \text{There is not sufficient evidence to warrant rejection of the claim that all 5 categories are equally likely to be selected.} \][/tex]

Thus, our final answers are:
[tex]\[ \begin{array}{|c|l|l|l|} \hline \text{Category} & \text{Observed Frequency} & \text{Expected Frequency} & \left(\frac{(O-E)^2}{E}\right)\\ \hline \text{A} & 18 & 13.00 & 1.923 \\ \hline \text{B} & 9 & 13.00 & 1.231 \\ \hline \text{C} & 15 & 13.00 & 0.308 \\ \hline \text{D} & 13 & 13.00 & 0.000 \\ \hline \text{E} & 10 & 13.00 & 0.692 \\ \hline \end{array} \][/tex]
[tex]\[ \chi^2 = 4.154 \][/tex]
[tex]\[ \text{df} = 4 \][/tex]
[tex]\[ p \text{-value} = 0.386 \][/tex]
The p-value is greater than [tex]\(\alpha\)[/tex].

We fail to reject the null hypothesis. There is not sufficient evidence to warrant rejection of the claim that all 5 categories are equally likely to be selected.