Averages And Range
Overview
How do you sum up a whole list of numbers in one value? You use an average. The mean, median and mode are three different ways to find a typical value, each with its own strengths, and the range tells you how spread out the data is. Together they let you describe and compare data sets quickly and fairly.
In this lesson you will calculate the mean, median, mode and range of a list, and learn when each average is the right choice. At Extended level you will go further: quartiles and the interquartile range to measure spread, the modal class of grouped data, and an estimated mean when the exact values are hidden inside class intervals.
Objectives
- Calculate the mean, median, mode and range for individual data and distinguish between the purposes for which these are used.
- Calculate the mean, median, mode, quartiles, range and interquartile range for individual data and distinguish between the purposes for which these are used. (Extended only)
- Calculate an estimate of the mean for grouped discrete or grouped continuous data. (Extended only)
- Identify the modal class from a grouped frequency distribution. (Extended only)
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Lesson Evaluation
Congratulations on completing the lesson on Averages And Range. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Find the mean of 4, 7, 7, 9, 13. A. 7 B. 8 C. 9 D. 40 Answer: B
- Find the median of 4, 7, 7, 9, 13. A. 4 B. 7 C. 8 D. 9 Answer: B
- Find the range of 4, 7, 7, 9, 13. A. 4 B. 7 C. 9 D. 13 Answer: C
- For the ordered data 3, 5, 6, 8, 9, 11, 14, what is the interquartile range? A. 3 B. 5 C. 6 D. 11 Answer: C
- For grouped data with classes 0<=t<10 (f=4), 10<=t<20 (f=10), 20<=t<30 (f=6), what is the modal class? A. 0 <= t < 10 B. 10 <= t < 20 C. 20 <= t < 30 D. all equal Answer: B
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Recommended Books
Further learning from open sources
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Textbook section
Measures of the Center of the Data
The "center" of a data set is also a way of describing location. The two most widely used measures of the "center" of the data are the mean (average) and the median . To calculate the mean weight of 50 people, add the 50 weights together and divide by 50. To find the median weight of the 50 people,
"Introductory Statistics: Measures of the Center of the Data" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/introductory-statistics/pages/2-5-measures-of-the-center-of-the-data. Access for free at https://openstax.org/books/introductory-statistics/pages/1-introduction
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Textbook section
Measures of the Location of the Data
The common measures of location are quartiles and percentiles Quartiles are special percentiles. The first quartile, Q 1 , is the same as the 25 th percentile, and the third quartile, Q 3 , is the same as the 75 th percentile. The median, M , is called both the second quartile and the 50 th percenti
"Introductory Statistics: Measures of the Location of the Data" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/introductory-statistics/pages/2-3-measures-of-the-location-of-the-data. Access for free at https://openstax.org/books/introductory-statistics/pages/1-introduction
Published by other organisations under open licences, credited as they ask. Links open their websites.
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