Find expert answers and community support for all your questions on IDNLearn.com. Get the information you need from our community of experts who provide accurate and thorough answers to all your questions.

Manufacturers are testing a die to make sure that it is fair (has a uniform distribution). They roll the die 78 times and record the outcomes in the table below. They conduct a chi-square Goodness-of-Fit hypothesis test at the [tex]$1\%$[/tex] significance level.

\begin{tabular}{|c|c|c|c|c|c|c|}
\hline Outcome & 1 & 2 & 3 & 4 & 5 & 6 \\
\hline Expected & 13 & 13 & 13 & 13 & 13 & 13 \\
\hline Observed & 7 & 10 & 14 & 16 & 9 & 22 \\
\hline
\end{tabular}

(a) The null and alternative hypotheses are:
- [tex]$H_0$[/tex] : The die has the uniform distribution.
- [tex]$H_a$[/tex] : The die does not have the uniform distribution.

(b) Compute the test statistic, rounded to three decimal places.

Provide your answer below:
Test Statistic [tex]$=$[/tex] [tex]$\square$[/tex]


Sagot :

To conduct a chi-square Goodness-of-Fit test, we follow a standard methodology:

1. Set up the hypotheses:
- Null hypothesis ([tex]\( H_0 \)[/tex]): The die has a uniform distribution.
- Alternative hypothesis ([tex]\( H_a \)[/tex]): The die does not have a uniform distribution.

2. Observed and expected frequencies:
- Observed counts: [tex]\([7, 10, 14, 16, 9, 22]\)[/tex]
- Expected counts: [tex]\([13, 13, 13, 13, 13, 13]\)[/tex]

3. Calculate the chi-square test statistic ([tex]\( \chi^2 \)[/tex]):
[tex]\[ \chi^2 = \sum \frac{(O_i - E_i)^2}{E_i} \][/tex]
where [tex]\( O_i \)[/tex] is the observed frequency and [tex]\( E_i \)[/tex] is the expected frequency.

4. Compute the individual components:
- For outcome 1: [tex]\(\frac{(7 - 13)^2}{13} = \frac{36}{13}\)[/tex]
- For outcome 2: [tex]\(\frac{(10 - 13)^2}{13} = \frac{9}{13}\)[/tex]
- For outcome 3: [tex]\(\frac{(14 - 13)^2}{13} = \frac{1}{13}\)[/tex]
- For outcome 4: [tex]\(\frac{(16 - 13)^2}{13} = \frac{9}{13}\)[/tex]
- For outcome 5: [tex]\(\frac{(9 - 13)^2}{13} = \frac{16}{13}\)[/tex]
- For outcome 6: [tex]\(\frac{(22 - 13)^2}{13} = \frac{81}{13}\)[/tex]

5. Sum these components:
[tex]\[ \chi^2 = \frac{36}{13} + \frac{9}{13} + \frac{1}{13} + \frac{9}{13} + \frac{16}{13} + \frac{81}{13} \][/tex]
[tex]\[ \chi^2 = \frac{36 + 9 + 1 + 9 + 16 + 81}{13} = \frac{152}{13} \approx 11.692 \][/tex]

So, the test statistic [tex]\( \chi^2 \)[/tex] rounded to three decimal places is:
[tex]\[ \boxed{11.692} \][/tex]