Questions: Refer to the accompanying data display that results from a simple random sample of times (minutes) between eruptions of the Old Faithful geyser. The confidence level of 95% was used. Complete parts (a) and (b) below. TInterval (85.74,91.76) x̄=88.75 Sx=8.897431411 n=36 a. Express the confidence interval in the format that uses the "less than" symbol. Round the confidence interval limits given that the original times are all rounded to one decimal place. min <μ< min (Round to two decimal places as needed.)

Refer to the accompanying data display that results from a simple random sample of times (minutes) between eruptions of the Old Faithful geyser. The confidence level of 95% was used. Complete parts (a) and (b) below.

TInterval
(85.74,91.76)
x̄=88.75
Sx=8.897431411
n=36

a. Express the confidence interval in the format that uses the "less than" symbol. Round the confidence interval limits given that the original times are all rounded to one decimal place.
min <μ< min
(Round to two decimal places as needed.)
Transcript text: Refer to the accompanying data display that results from a simple random sample of times (minutes) between eruptions of the Old Faithful geyser. The confidence level of $95 \%$ was used. Complete parts (a) and (b) below. TInterval \[ \begin{array}{l} (85.74,91.76) \\ \bar{x}=88.75 \\ S x=8.897431411 \\ n=36 \end{array} \] a. Express the confidence interval in the format that uses the "less than" symbol. Round the confidence interval limits given that the original times are all rounded to one decimal place. $\square$ $\square$ $\min <\mu<$ min (Round to two decimal places as needed.)
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Solution

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Solution Steps

Step 1: Calculate the Margin of Error

To determine the margin of error for the confidence interval, we use the formula:

\[ \text{Margin of Error} = \frac{Z \times \sigma}{\sqrt{n}} \]

where:

  • \( Z = 1.96 \) (the Z-score for a 95% confidence level),
  • \( \sigma = 8.897431411 \) (the sample standard deviation),
  • \( n = 36 \) (the sample size).

Substituting the values, we have:

\[ \text{Margin of Error} = \frac{1.96 \times 8.897431411}{\sqrt{36}} = 2.91 \]

Step 2: Determine the Confidence Interval

The confidence interval for the population mean \( \mu \) is calculated using the sample mean and the margin of error:

\[ \bar{x} - \text{Margin of Error} < \mu < \bar{x} + \text{Margin of Error} \]

Substituting the values:

\[ 88.75 - 2.91 < \mu < 88.75 + 2.91 \]

Calculating the limits:

\[ 85.84 < \mu < 91.66 \]

Final Answer

The confidence interval can be expressed as:

\[ \boxed{85.84 < \mu < 91.66} \]

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