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 3m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 12m
- 9. Hypothesis Testing for One Sample1h 1m
- 10. Hypothesis Testing for Two Samples2h 8m
- 11. Correlation48m
- 12. Regression1h 4m
- 13. Chi-Square Tests & Goodness of Fit1h 20m
- 14. ANOVA1h 0m
3. Describing Data Numerically
Median
Problem 2.3.25
Textbook Question
Using and Interpreting Concepts
Finding and Discussing the Mean, Median, and Mode In Exercises 17–34, find the mean, the median, and the mode of the data, if possible. If any measure cannot be found or does not represent the center of the data, explain why.
Power Failures The durations (in minutes) of power failures at a residence in the last 10 years
18 26 45 75 125 80 33
40 44 49 89 80 96 125
12 61 31 63 103 28 19

1
Step 1: Organize the data set in ascending order to make calculations easier. The given durations are: 12, 18, 19, 26, 28, 31, 40, 44, 45, 49, 61, 63, 75, 80, 80, 89, 96, 103, 125, 125.
Step 2: Calculate the mean (average). Add all the values together and divide by the total number of values. Use the formula: , where represents each data point and is the total number of data points.
Step 3: Find the median. The median is the middle value when the data is ordered. If the number of data points is odd, the median is the middle value. If even, the median is the average of the two middle values. Since there are 20 values, find the average of the 10th and 11th values in the ordered list.
Step 4: Determine the mode. The mode is the value that appears most frequently in the data set. Count the frequency of each value to identify the mode. If no value repeats, the data set has no mode.
Step 5: Interpret the results. Discuss whether the mean, median, and mode represent the center of the data effectively. Consider factors such as the presence of outliers (e.g., very high or very low values) and whether the measures provide a meaningful summary of the data distribution.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Mean
The mean, or average, is calculated by summing all the values in a dataset and dividing by the number of values. It provides a central value that represents the dataset as a whole. However, the mean can be sensitive to extreme values (outliers), which may skew the result and not accurately reflect the data's center.
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Median
The median is the middle value of a dataset when the values are arranged in ascending order. If there is an even number of observations, the median is the average of the two middle values. The median is a robust measure of central tendency, as it is less affected by outliers and skewed data compared to the mean.
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Mode
The mode is the value that appears most frequently in a dataset. A dataset may have one mode (unimodal), more than one mode (bimodal or multimodal), or no mode at all if all values occur with the same frequency. The mode is particularly useful for categorical data where we wish to know the most common category.
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