College

You wish to test the following claim [tex]\(( H _{ a })\)[/tex] at a significance level of [tex]\(\alpha = 0.01\)[/tex].

[tex]
\[
\begin{array}{l}
H_{o}: \mu = 83.8 \\
H_{a}: \mu \neq 83.8
\end{array}
\]
[/tex]

You believe the population is normally distributed, but you do not know the standard deviation. You obtain the following sample of data:

[tex]
\[
\begin{array}{|r|r|r|r|r|}
\hline
61.6 & 113.7 & 64.4 & 75.1 & 75.5 \\
\hline
52 & 60.9 & 82.9 & 39.7 & 64.4 \\
\hline
87.4 & 88.5 & 64.4 & 85.1 & 63.3 \\
\hline
65 & 46.8 & 100.2 & 60.2 & 95.4 \\
\hline
82.4 & 89 & 104.6 & 68.4 & 79.1 \\
\hline
84.2 & 53.3 & 60.9 & 72.7 & 90.1 \\
\hline
44.1 & 53.3 & 66.5 & 65 & 95.4 \\
\hline
109.4 & 84.6 & 58 & 84.6 & 78.7 \\
\hline
55.4 & 84.2 & 62.8 & 79.9 & 90.1 \\
\hline
99.1 & 86 & 99.1 & 59.5 & 91.3 \\
\hline
52 & 79.1 & 61.6 & 88 & 44.1 \\
\hline
\end{array}
\]
[/tex]

What is the test statistic for this sample? (Report the answer accurate to three decimal places.)

Test statistic [tex]\(=\)[/tex] [tex]\(\square\)[/tex]

Answer :

To determine the test statistic for this sample with the given hypothesis, we'll go through the process step-by-step.

### Step 1: Collect the Sample Data
The sample consists of the following data points:
61.6, 113.7, 64.4, 75.1, 75.5, 52, 60.9, 82.9, 39.7, 64.4, 87.4, 88.5, 64.4, 85.1, 63.3, 65, 46.8, 100.2, 60.2, 95.4, 82.4, 89, 104.6, 68.4, 79.1, 84.2, 53.3, 60.9, 72.7, 90.1, 44.1, 53.3, 66.5, 65, 95.4, 109.4, 84.6, 58, 84.6, 78.7, 55.4, 84.2, 62.8, 79.9, 90.1, 99.1, 86, 99.1, 59.5, 91.3, 52, 79.1, 61.6, 88, 44.1

### Step 2: Calculate the Sample Mean
First, we calculate the sample mean [tex]\(\bar{x}\)[/tex]:
[tex]\[
\bar{x} = \frac{\text{sum of all sample values}}{\text{number of samples}}
\][/tex]
The sample mean is 74.6.

### Step 3: Calculate the Sample Standard Deviation
The sample standard deviation [tex]\(s\)[/tex] is calculated using the formula:
[tex]\[
s = \sqrt{\frac{\sum (x_i - \bar{x})^2}{n - 1}}
\][/tex]
where [tex]\(x_i\)[/tex] are the sample values and [tex]\(n\)[/tex] is the number of samples.

The sample standard deviation is 17.821 (rounded to three decimal places).

### Step 4: Calculate the Test Statistic
The test statistic is calculated using the formula for the t-statistic:
[tex]\[
t = \frac{\bar{x} - \mu}{s / \sqrt{n}}
\][/tex]
where:
- [tex]\(\bar{x}\)[/tex] is the sample mean,
- [tex]\(\mu\)[/tex] is the population mean (83.8 in this case),
- [tex]\(s\)[/tex] is the sample standard deviation,
- [tex]\(n\)[/tex] is the sample size.

Given the calculations:
- [tex]\(\bar{x} = 74.6\)[/tex]
- [tex]\(\mu = 83.8\)[/tex]
- [tex]\(s = 17.821\)[/tex]
- [tex]\(n = 55\)[/tex]

Substituting these into the formula gives us the test statistic:
[tex]\[
t = \frac{74.6 - 83.8}{17.821 / \sqrt{55}} = -3.829
\][/tex]

Thus, the test statistic is [tex]\(-3.829\)[/tex] (rounded to three decimal places).

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