Problem

Assume that a sample is used to estimate a population mean $\mu$. Find the $98 \%$ confidence interval for a sample of size 972 with a mean of 72.6 and a standard deviation of 5.3. Enter your answer as a tri-linear inequality accurate to 3 decimal places. \[ <\mu< \] Question Help: Message instructor

Solution

Step 1 :We are given a sample size of 972, a sample mean of 72.6, a standard deviation of 5.3, and we are asked to find the 98% confidence interval for the population mean.

Step 2 :The formula for the confidence interval for a population mean is \(\bar{x} \pm Z \frac{\sigma}{\sqrt{n}}\), where \(\bar{x}\) is the sample mean, \(Z\) is the Z-score, \(\sigma\) is the standard deviation of the population, and \(n\) is the sample size.

Step 3 :For a 98% confidence level, the Z-score is approximately 2.33.

Step 4 :Substituting the given values into the formula, we get \(72.6 \pm 2.33 \frac{5.3}{\sqrt{972}}\).

Step 5 :Solving this, we get a margin of error of approximately 0.396.

Step 6 :Subtracting this margin of error from the sample mean, we get a lower bound of 72.204.

Step 7 :Adding this margin of error to the sample mean, we get an upper bound of 72.996.

Step 8 :Thus, the 98% confidence interval for the population mean \(\mu\) is given by the inequality \(72.204 < \mu < 72.996\).

Step 9 :\(\boxed{72.204 < \mu < 72.996}\) is the final answer.

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Source: https://solvelyapp.com/problems/17519/

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