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A clothing retailer is interested in the average waist size of men. A sample is taken with the results given:

[tex]\[
\begin{tabular}{|l|r|}
\hline \multicolumn{2}{|c|}{ Statistics } \\
\hline Mean & 41.39 \\
\hline Standard Error & 1.033 \\
\hline Median & 41 \\
\hline Mode & 41 \\
\hline Standard Deviation & 5.466 \\
\hline Sample Variance & 29.88 \\
\hline Kurtosis & 0.474 \\
\hline Skewness & 0.608 \\
\hline Range & 21 \\
\hline Minimum & 32 \\
\hline Maximum & 53 \\
\hline Sum & 1159 \\
\hline Count & 60 \\
\hline Confidence Level (95.0\%) & 2.119 \\
\hline
\end{tabular}
\][/tex]

1. What is the sample statistic? [tex]$\bar{x}=$[/tex] (Ex: 1.23)

2. What is the point estimate for the average waist size? [tex]$\square$[/tex]

3. What is the level of confidence as a decimal? (Ex: 0.55)

4. What is the margin of error? (Ex: 1.234)

5. What is the confidence interval? ( [tex]$\square$[/tex], [tex]$\square$[/tex] )


Sagot :

Let's go through the problem step-by-step to find the required values.

1. Sample Statistic ([tex]\(\bar{x}\)[/tex])

This is the mean of the sample data. Based on the given information:

[tex]\(\bar{x} = 41.39\)[/tex]

2. Point Estimate for the Average Waist Size

The point estimate for the population parameter (the average waist size) is also typically the sample mean:

[tex]\(\text{Point Estimate} = 41.39\)[/tex]

3. Level of Confidence as a Decimal

The given confidence level is 95.0%. Expressed as a decimal, this is:

[tex]\(\text{Level of Confidence} = 0.95\)[/tex]

4. Margin of Error

The margin of error is calculated using the formula:

[tex]\[ \text{Margin of Error} = \text{Confidence Level} \times \text{Standard Error} \][/tex]

Using the data provided:
[tex]\[ \text{Confidence Level} = 2.119 \][/tex]
[tex]\[ \text{Standard Error} = 1.033 \][/tex]

[tex]\[ \text{Margin of Error} = 2.119 \times 1.033 = 2.188927 \][/tex]

5. Confidence Interval

The confidence interval is calculated as:

[tex]\[ \text{Confidence Interval} = (\text{Mean} - \text{Margin of Error}, \text{Mean} + \text{Margin of Error}) \][/tex]

Using the given mean and the calculated margin of error:

[tex]\[ \text{Lower Bound} = 41.39 - 2.188927 = 39.201073 \][/tex]
[tex]\[ \text{Upper Bound} = 41.39 + 2.188927 = 43.578927 \][/tex]

So, the confidence interval is:

[tex]\[ (39.201073, 43.578927) \][/tex]

Putting it all together, we have:

- Sample Statistic [tex]\(\bar{x} = 41.39\)[/tex]
- Point Estimate for the Average Waist Size [tex]\(= 41.39\)[/tex]
- Level of Confidence as a Decimal [tex]\(= 0.95\)[/tex]
- Margin of Error [tex]\(= 2.188927\)[/tex]
- Confidence Interval [tex]\(= (39.201073, 43.578927)\)[/tex]

Hence, the detailed solution for each part is:

- Sample Statistic: [tex]\(\bar{x} = 41.39\)[/tex]
- Point Estimate for the Average Waist Size: [tex]\(41.39\)[/tex]
- Level of Confidence as a decimal: [tex]\(0.95\)[/tex]
- Margin of Error: [tex]\(2.188927\)[/tex]
- Confidence Interval: [tex]\((39.201073, 43.578927)\)[/tex]