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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 2.3.9

Graphical Analysis In Exercises 9–12, determine whether the approximate shape of the distribution in the histogram is symmetric, uniform, skewed left, skewed right, or none of these. Justify your answer.
Histogram displaying data distribution with bars representing frequencies for ranges 25,000 to 85,000.

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Observe the histogram provided. Note the distribution of frequencies across the bins, which represent ranges of values (e.g., 25,000 to 85,000).
Identify the general trend of the bars. In this histogram, the bars are tallest on the left side and gradually decrease in height as you move to the right.
Understand the concept of skewness. A distribution is skewed right if the tail extends to the right (towards higher values) and skewed left if the tail extends to the left (towards lower values). Symmetric distributions have equal tails on both sides, and uniform distributions have bars of roughly equal height.
Compare the histogram's shape to these definitions. The histogram shows a long tail extending to the right, indicating that the distribution is skewed right.
Justify the conclusion: The majority of the data is concentrated on the lower end (left side), with fewer occurrences as the values increase, which is characteristic of a right-skewed distribution.

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Key Concepts

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

Histogram

A histogram is a graphical representation of the distribution of numerical data, where the data is divided into intervals (bins) and the frequency of data points within each interval is represented by the height of bars. It helps visualize the shape of the data distribution, making it easier to identify patterns such as symmetry, skewness, and modality.
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Guided course
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Intro to Histograms

Distribution Shape

The shape of a distribution refers to the way data points are spread across the range of values. Common shapes include symmetric (equal on both sides), uniform (equal frequency across intervals), skewed left (tail on the left), and skewed right (tail on the right). Understanding the shape is crucial for interpreting data characteristics and making statistical inferences.
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Uniform Distribution

Skewness

Skewness measures the asymmetry of a distribution. A distribution is skewed left if it has a longer tail on the left side, indicating that most data points are concentrated on the right. Conversely, a skewed right distribution has a longer tail on the right side. Identifying skewness helps in understanding the underlying data trends and potential outliers.
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Creating Frequency Polygons
Related Practice
Textbook Question

Finding the Sample Mean and Standard Deviation for Grouped Data In Exercises 39 and 40, make a frequency distribution for the data. Then use the table to find the sample mean and the sample standard deviation of the data set.


3 3 5 3 8 0 3 9 6 6 7 1 6 3 2 6 9 1 8 5 0 2 3 4 9

5 8 1 9 7 6 9 6 7 0 6 3 8 6 8 7 3 8 9 3 7 2 4 4 1

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Textbook Question

Graphical Analysis In Exercises 9–12, determine whether the approximate shape of the distribution in the histogram is symmetric, uniform, skewed left, skewed right, or none of these. Justify your answer.

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Textbook Question

Putting Graphs in Context In Exercises 5–8, match the plot with the description of the sample.

a. Times (in minutes) it takes a sample of employees to drive to work

b. Grade point averages of a sample of students with finance majors

c. Top speeds (in miles per hour) of a sample of high-performance sports cars

d. Ages (in years) of a sample of residents of a retirement home


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Textbook Question

Graphical Analysis In Exercises 41 and 42, the midpoints A, B, and C are marked on the histograms at the left. Match them with the indicated z-scores. Which z-scores, if any, would be considered unusual?


z = 0, z = 2.14, z = −1.43


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Textbook Question

Using the Empirical Rule In Exercises 29–34, use the Empirical Rule.


The speeds for eight vehicles are listed. Using the sample statistics from Exercise 29, determine which of the data entries are unusual. Are any of the data entries very unusual? Explain your reasoning.

70, 78, 62, 71, 65, 76, 82, 64

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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.


Prices (in dollars) of Flights from Chicago to Alanta

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