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Ch. 2 - Descriptive Statistics
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470Not the one you use?Change textbook
Chapter 2, Problem 2.5.17a

Drawing a Box-and-Whisker Plot In Exercises 15–18,
(a) find the five-number summary


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Step 1: Organize the data set in ascending order. The given data set is: 1, 2, 2, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 9, 9.
Step 2: Identify the minimum value (smallest number in the data set) and the maximum value (largest number in the data set).
Step 3: Find the median (Q2), which is the middle value of the data set. If the data set has an even number of values, the median is the average of the two middle numbers.
Step 4: Determine the first quartile (Q1), which is the median of the lower half of the data (excluding the overall median). Similarly, find the third quartile (Q3), which is the median of the upper half of the data.
Step 5: Use the five-number summary (minimum, Q1, median, Q3, maximum) to construct the box-and-whisker plot. The box represents Q1 to Q3, with a line at the median, and the whiskers extend to the minimum and maximum values.

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Key Concepts

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

Five-Number Summary

The five-number summary is a descriptive statistic that provides a quick overview of a dataset. It consists of the minimum, first quartile (Q1), median (Q2), third quartile (Q3), and maximum values. This summary helps in understanding the distribution and spread of the data, making it easier to identify outliers and the overall range.
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Box-and-Whisker Plot

A box-and-whisker plot, or box plot, visually represents the five-number summary of a dataset. It displays the minimum and maximum values as 'whiskers' and the quartiles as a 'box' in the middle. This plot is useful for comparing distributions between different datasets and identifying potential outliers.
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Quartiles

Quartiles are values that divide a dataset into four equal parts, each containing 25% of the data points. The first quartile (Q1) is the median of the lower half of the data, the second quartile (Q2) is the overall median, and the third quartile (Q3) is the median of the upper half. Understanding quartiles is essential for interpreting the spread and central tendency of the data.
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