A properly drawn random sample of one thousand individuals is used to estimate a population mean. The sampling error for the sample mean is roughly plus or minus what percent of the population mean (assuming a normal distribution and no prior knowledge of population standard deviation)?
Table of contents
- 1. Intro to Stats and Collecting Data1h 14m
- 2. Describing Data with Tables and Graphs1h 55m
- 3. Describing Data Numerically2h 5m
- 4. Probability2h 16m
- 5. Binomial Distribution & Discrete Random Variables3h 6m
- 6. Normal Distribution and Continuous Random Variables2h 11m
- 7. Sampling Distributions & Confidence Intervals: Mean3h 23m
- Sampling Distribution of the Sample Mean and Central Limit Theorem19m
- Distribution of Sample Mean - Excel23m
- Introduction to Confidence Intervals15m
- Confidence Intervals for Population Mean1h 18m
- Determining the Minimum Sample Size Required12m
- Finding Probabilities and T Critical Values - Excel28m
- Confidence Intervals for Population Means - Excel25m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 25m
- 9. Hypothesis Testing for One Sample3h 29m
- 10. Hypothesis Testing for Two Samples4h 50m
- Two Proportions1h 13m
- Two Proportions Hypothesis Test - Excel28m
- Two Means - Unknown, Unequal Variance1h 3m
- Two Means - Unknown Variances Hypothesis Test - Excel12m
- Two Means - Unknown, Equal Variance15m
- Two Means - Unknown, Equal Variances Hypothesis Test - Excel9m
- Two Means - Known Variance12m
- Two Means - Sigma Known Hypothesis Test - Excel21m
- Two Means - Matched Pairs (Dependent Samples)42m
- Matched Pairs Hypothesis Test - Excel12m
- 11. Correlation1h 24m
- 12. Regression1h 50m
- 13. Chi-Square Tests & Goodness of Fit2h 21m
- 14. ANOVA1h 57m
7. Sampling Distributions & Confidence Intervals: Mean
Confidence Intervals for Population Mean
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You want to purchase one of the new Altima. You randomly select 400 dealerships across the United States and find a mean of \$25,000. Assume a population standard deviation of \$2500. Construct and interpret a 94% confidence interval for the true mean price for the new Nissan Altima.
A
(24992.5, 25007.5); We are 94% confident that the true mean price for the new Nissan Altima falls between \$24992.5 and \$25007.5.
B
(24882.438, 25117.563); We are 94% confident that the true mean price for the new Nissan Altima falls between \$24882.438 and \$25117.563.
C
(24764.875, 25235.15); We are 94% confident that the true mean price for the new Nissan Altima falls between \$24764.875 and \$25235.15.
D
(24529.75, 25470.25); We are 94% confident that the true mean price for the new Nissan Altima falls between \$24529.75 and \$25470.25.
Verified step by step guidance1
Identify the sample mean (\( \bar{x} \)) and the population standard deviation (\( \sigma \)). Here, \( \bar{x} = 25000 \) and \( \sigma = 2500 \).
Determine the sample size (\( n \)), which is 400 in this case.
Select the confidence level, which is 94%. This will help you find the corresponding z-score from the standard normal distribution table. For a 94% confidence level, the z-score is approximately 1.88.
Calculate the standard error of the mean using the formula \( \text{SE} = \frac{\sigma}{\sqrt{n}} \). Substitute \( \sigma = 2500 \) and \( n = 400 \) into the formula.
Construct the confidence interval using the formula \( \bar{x} \pm z \times \text{SE} \). Substitute the values for \( \bar{x} \), \( z \), and \text{SE} to find the lower and upper bounds of the confidence interval.
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