Table of contents

1. Intro to Stats and Collecting Data55m
2. Describing Data with Tables and Graphs1h 55m
3. Describing Data Numerically1h 45m
4. Probability2h 16m
5. Binomial Distribution & Discrete Random Variables2h 33m
6. Normal Distribution and Continuous Random Variables1h 38m
7. Sampling Distributions & Confidence Intervals: Mean1h 53m
8. Sampling Distributions & Confidence Intervals: Proportion1h 12m
- Sampling Distribution of Sample Proportion
  29m
- Confidence Intervals for Population Proportion
  42m
9. Hypothesis Testing for One Sample2h 19m
10. Hypothesis Testing for Two Samples3h 22m
11. Correlation1h 6m
12. Regression1h 4m
13. Chi-Square Tests & Goodness of Fit1h 20m
14. ANOVA1h 0m

7. Sampling Distributions & Confidence Intervals: Mean

Confidence Intervals for Population Mean

Statistics

7. Sampling Distributions & Confidence Intervals: Mean

Confidence Intervals for Population Mean

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1:31 minutes

Problem 6.2.13

Textbook Question

In Exercises 13 and 14, use the confidence interval to find the margin of error and the sample mean.
(14.7, 22.1)

Verified step by step guidance

Step 1: Understand the problem. The confidence interval is given as (14.7, 22.1). The goal is to find the margin of error and the sample mean. The confidence interval represents the range of values within which the true population parameter is expected to lie.

Step 2: Recall the formula for the margin of error. The margin of error (E) is half the width of the confidence interval. Mathematically, it is calculated as:

E = \frac{\text{Upper Limit} - \text{Lower Limit}}{2}

Step 3: Recall the formula for the sample mean. The sample mean ($\bar{x}$) is the midpoint of the confidence interval. Mathematically, it is calculated as:

\bar{x} = \frac{\text{Upper Limit} + \text{Lower Limit}}{2}

Step 4: Substitute the given values into the formulas. For the margin of error, substitute 22.1 as the upper limit and 14.7 as the lower limit into the formula for E. For the sample mean, substitute the same values into the formula for $\bar{x}$.

Step 5: Simplify the expressions to find the numerical values of the margin of error and the sample mean. This will give you the final results.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Confidence Interval

A confidence interval is a range of values, derived from sample statistics, that is likely to contain the true population parameter. It is expressed as an interval (e.g., (14.7, 22.1)) and is associated with a confidence level, typically 95% or 99%. This means that if we were to take many samples and build intervals in this way, a certain percentage of them would contain the true parameter.

Margin of Error

The margin of error quantifies the uncertainty associated with a sample estimate. It is calculated as half the width of the confidence interval, representing the maximum expected difference between the sample statistic and the population parameter. In the given interval (14.7, 22.1), the margin of error would be (22.1 - 14.7) / 2 = 3.7.

Sample Mean

The sample mean is the average of a set of values obtained from a sample, serving as an estimate of the population mean. It is calculated by summing all sample values and dividing by the number of observations. In the context of the confidence interval, the sample mean can be found as the midpoint of the interval, which is (14.7 + 22.1) / 2 = 18.4.

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