Class 9 Maths Chapter 7, The Mathematics of Maybe: Introduction to Probability, treats probability as a measurement, like length or area, but of how likely an event is. Its examples are everyday ones: will it rain today, will the school win tomorrow’s hockey match, will your name come out of the lucky draw for the assembly. It covers experimental and theoretical probability, sample spaces, events and tree diagrams.
What Class 9 Maths Chapter 7 Covers
7.1 What is Probability? places likelihood on a scale from 0 (impossible) to 1 (certain) and writes it as P(E).
7.2 Measuring Probability Objectively compares experimental probability (times the event occurred ÷ number of trials) with theoretical probability (favourable outcomes ÷ possible outcomes). Boxes on Snakes and Ladders, sampling, the gambler’s fallacy and what makes a coin fair sit alongside.
7.3 Elements of Probability: Sample Spaces and Events lists all outcomes of an experiment as a set S and defines an event as one or more of those outcomes.
7.4 Tree Diagrams lays out repeated experiments, such as tossing a coin twice, to count outcomes like two heads.
Exercises in Chapter 7
- Exercise Sets 7.1 to 7.4 after each section.
- End-of-Chapter Exercises over four pages, followed by the chapter summary of all formulas.
Read Class 9 Maths Chapter 7 Online
More Chapters
- Previous: Chapter 6: Measuring Space: Perimeter and Area
- Next: Chapter 8: Predicting What Comes Next: Exploring Sequences and Progressions
- Hindi medium: Class 9 Maths Chapter 7 PDF in Hindi (संभावनाओं का गणित — प्रायिकता का परिचय)
- All Maths chapters and the other Class 9 books: Class 9 NCERT books 2026-27
- All Class 1 to 12 NCERT Textbooks: NCERT Books PDF (Class 1–12)
FAQ
What is the difference between experimental and theoretical probability?
Experimental probability comes from repeating an experiment: times the event happened divided by total trials. Theoretical probability assumes equally likely outcomes: favourable outcomes divided by possible outcomes.
What is the gambler’s fallacy?
The belief that after a random event has happened many times in a row, the opposite outcome becomes more likely. Chapter 7 explains why a fair coin has no memory.