Chapter 10: How Quantities Combine: Understanding Data - Solutions
Chapter solutions are on NCERT Archive
Step-by-step solutions for this chapter now live on NCERT Archive, along with the chapter itself. Use the buttons below to open them.
About Chapter 10 (How Quantities Combine: Understanding Data)
Chapter 10 (How Quantities Combine: Understanding Data) is chapter 10 of 14 in the new edition of Ganita Manjari (NCERT Class 9 Mathematics), a textbook for Class 9 students at the Secondary stage. This is the new edition, the textbook brought out under the NEP 2020 / NCF-SE 2023 syllabus rollout.
Chapter 10 extends the idea of the average to the weighted average. It shows why an average of averages must account for group sizes, applies weighted means to mixtures, custom weights, ratings and marks, and then introduces stacked bar charts and 100% stacked bar charts as ways to visualise and interpret data, including what each chart can and cannot tell us.
In the book it comes after Chapter 9 (Propositions and their Converses) and before Chapter 11 (The World of Algorithms), so it helps to be comfortable with the earlier chapters before starting it.
Topics covered
- Average of averages
- Mixtures and concentration
- Weighted mean with custom weights
- Stacked bar charts
- 100% stacked bar charts and their interpretation
What the solutions on NCERT Archive include
NCERT Archive is our dedicated site for NCERT textbooks and solutions, Class 1 to 12. The solutions page for Chapter 10 (How Quantities Combine: Understanding Data) there gives chapter-wise answers to the questions of Ganita Manjari (NCERT Class 9 Mathematics), written to follow the order of the textbook, and links back to the chapter itself. Use the buttons above to go to it.
How to study How Quantities Combine: Understanding Data
- Read the worked examples before the exercises and copy out each step in your own hand.
- Attempt every exercise question yourself first; open the solution only to check your method or when you are stuck.
- Keep a short list of formulas and definitions from the chapter and revise it before tests.
- Redo the questions you got wrong after a day or two, without looking at the solution.
Frequently Asked Questions
Which book is Chapter 10 (How Quantities Combine: Understanding Data) of Class 9 Mathematics from?
It is from the new edition of Ganita Manjari (NCERT Class 9 Mathematics). The book has 14 chapters, and this is chapter 10.
Where can I find the solutions for Chapter 10 (How Quantities Combine: Understanding Data) of Class 9 Mathematics?
On NCERT Archive. Press the "Open Chapter Solutions" button on this page and you will land on the solutions page for this chapter there.
Is this the new edition or the old edition?
This page is for the new edition. If your school still uses the earlier textbook, use the Old Edition switch at the top of the page.
Is it free to use?
Yes. Scholar Donkey and NCERT Archive are free to use and need no login.