NCERT Solutions Class 9 Maths Chapter 7 — The Mathematics of Maybe: Introduction to Probability#
Chapter 7 introduces probability — a way to measure how likely an event is. Using the empirical definition $P(E) = \dfrac{\text{number of favourable trials}}{\text{total number of trials}}$, you will analyse coin tosses, dice rolls, and real-life data to quantify uncertainty.
Exercises#
- Exercise Set 7.1 — Ranking events from impossible to certain (1 question)
- Exercise Set 7.2 — Experimental and theoretical probability, estimating from samples (6 questions)
- Exercise Set 7.3 — Sample spaces and events (3 questions)
- Exercise Set 7.4 — Tree diagrams (2 questions)
- End-of-Chapter Exercises — Coins, dice, cards, spinners, drawing without replacement, geometric probability (16 questions)
What you will learn#
- Placing events on a scale from impossible to certain.
- Experimental probability from trials and data, and theoretical probability from equally likely outcomes.
- Writing sample spaces and events.
- Tree diagrams for experiments in two or more stages.
Key formulas and results#
- Theoretical: $P(E) = \dfrac{\text{favourable outcomes}}{\text{all equally likely outcomes}}$.
- Experimental: $P(E) \approx \dfrac{\text{number of times } E \text{ happened}}{\text{number of trials}}$.
Read and revise#
- NCERT Class 9 Maths Chapter 7 (PDF) — the Ganita Manjari Part I chapter itself.
- All Class 9 Maths chapters from Ganita Manjari Part I and Part II.
Frequently asked questions#
How many exercises are in Class 9 Maths Chapter 7?
Four exercise sets — 7.1 (1 question), 7.2 (6 questions), 7.3 (3 questions) and 7.4 (2 questions) — plus 16 end-of-chapter exercises. Every question is solved step by step here.
What is the difference between experimental and theoretical probability?
Experimental probability comes from actually repeating an experiment and counting results. Theoretical probability comes from reasoning about equally likely outcomes. With more and more trials, the experimental value usually gets closer to the theoretical one.