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Revision Notes

Mean and Median — Revision Notes

ICSE · Class 9 · Mathematics

Mean and Median revision notes for ICSE Class 9 Mathematics: 4 topics in quick points. Part of the ICSE Class 9 Mathematics syllabus.

41 questions22 flashcards15 formulas & key relations5 concepts

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An illustration showing the formula for calculating the mean of ungrouped data, with an example set of numbers and their sum and count.
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Key Topics to Revise

1

Mean of Ungrouped Data

  • Mean is the sum of all observations divided by the total number of observations.
  • Mean, arithmetic mean, and average are the same.
  • The symbol Σx stands for the sum of all observations.
2

Properties of Mean

  • The sum of deviations from the mean is zero.
  • If each observation is increased by a constant, the mean increases by the same constant.
  • If each observation is decreased by a constant, the mean decreases by the same constant.
3

Mean: Solved Examples and Short Questions

  • The mean of 7, 5, 8, p, 11 equal to 8 gives the value of p as 9.
  • For 100 observations with mean 30, correcting 32 and 12 to 23 and 11 gives correct mean 29.9.
  • If mean of 15 observations is 200 and excluding one gives mean 198 for remaining 14, the excluded observation is 228.
4

Median of Ungrouped Data

  • Median is the middle term of a data set after arranging values in order.
  • Step 1 is to arrange data in ascending or descending order.
  • Step 2 is to count the total number of observations n.

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Full Notes

Key Concepts

Mean is the sum of allΣxi means the sum of allThe sum of deviations of allIf each observation is increased byIf each observation is decreased by

Frequently Asked Questions

What are the important topics in Mean and Median for ICSE Class 9 Mathematics?
Key topics in Mean and Median include Mean of Ungrouped Data, Properties of Mean, Mean: Solved Examples and Short Questions, Median of Ungrouped Data. Study these first, then practise questions on each for Class 9 exams.
How should I revise Mean and Median for Class 9 exams?
Learn the core ideas first, then work through the 41 practice questions on Mean and Median. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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