Problem

(CO 4) In a sample of 15 stuffed animals, you find that they weigh an average of 8.56 ounces with a standard deviation of 0.06 ounces. Find the $92 \%$ confidence interval.
$(8.527,8.593)$
$(8.526,8.594)$
$(8.531,8.589)$
$(8.52 \times, 8.599)$

Answer

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Answer

Final Answer: The 92% confidence interval is \(\boxed{(8.531,8.589)}\).

Steps

Step 1 :Given values are: sample mean \(x_{bar} = 8.56\), standard deviation \(s = 0.06\), sample size \(n = 15\), and Z-score for 92% confidence level \(Z = 1.75\).

Step 2 :Calculate the margin of error using the formula: \(Z \times \frac{s}{\sqrt{n}}\).

Step 3 :Substitute the given values into the formula to get the margin of error: \(1.75 \times \frac{0.06}{\sqrt{15}} = 0.027110883423451915\).

Step 4 :Calculate the confidence interval using the formula: \(x_{bar} \pm\) margin of error.

Step 5 :Substitute the values into the formula to get the confidence interval: \(8.56 - 0.027110883423451915 = 8.532889116576548\) and \(8.56 + 0.027110883423451915 = 8.587110883423453\).

Step 6 :The 92% confidence interval is \((8.532889116576548, 8.587110883423453)\), which can be approximated to \((8.533, 8.587)\).

Step 7 :Comparing the calculated confidence interval with the given options, it is closest to the option \((8.531,8.589)\).

Step 8 :Final Answer: The 92% confidence interval is \(\boxed{(8.531,8.589)}\).

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