A simple random sample of 20 items resulted in a sample mean of 20. The population standard deviation is = 6. Round your answers to two decimal places. a. What is the standard error of the mean, o? b. At 95% confidence, what is the margin of error?

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**Sample Size Calculation and Confidence Intervals**

A simple random sample of 20 items resulted in a sample mean of 20. The population standard deviation is \( \sigma = 6 \). Round your answers to two decimal places.

a. **What is the standard error of the mean, \( \sigma_{\bar{x}} \)?**

\[ \sigma_{\bar{x}} = \frac{\sigma}{\sqrt{n}} \]
(Sample size \( n = 20 \))

b. **At 95% confidence, what is the margin of error?**

\[ \text{Margin of Error} = Z \times \sigma_{\bar{x}} \]
(For 95% confidence, \( Z \approx 1.96 \))
Transcribed Image Text:**Sample Size Calculation and Confidence Intervals** A simple random sample of 20 items resulted in a sample mean of 20. The population standard deviation is \( \sigma = 6 \). Round your answers to two decimal places. a. **What is the standard error of the mean, \( \sigma_{\bar{x}} \)?** \[ \sigma_{\bar{x}} = \frac{\sigma}{\sqrt{n}} \] (Sample size \( n = 20 \)) b. **At 95% confidence, what is the margin of error?** \[ \text{Margin of Error} = Z \times \sigma_{\bar{x}} \] (For 95% confidence, \( Z \approx 1.96 \))
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