The Mathematics of Maybe: Introduction to Probability
NCERT Class 9 Maths • Chapter 7
Quick Answer
This Class 9 Maths chapter introduces probability, the measure of how likely an event is to happen. Students learn experimental (empirical) probability from real trials, the meaning of outcomes, events, and sample space, and how to express probability as a number between 0 and 1 using observed data from experiments like coin tosses and dice.
↓ Free PDF, NCERT solutions, summary, key terms, FAQs below.
Read Online
Loading PDF…
Key Terms
- Probability
- A number between 0 and 1 that measures how likely an event is to occur, with 0 meaning impossible and 1 meaning certain.
- Experiment
- An action or trial, such as tossing a coin or rolling a die, that produces one of several possible results.
- Outcome
- A single possible result of an experiment, like getting heads when a coin is tossed.
- Event
- A collection of one or more outcomes of an experiment, such as getting an even number on a die.
- Empirical Probability
- Probability based on the actual results of repeated trials, found by dividing favourable trials by total trials.
- Trial
- One performance of an experiment, such as one toss of a coin within many tosses.
- Favourable Outcome
- An outcome that matches the event whose probability is being measured.
Frequently Asked Questions
What is probability in Class 9 Maths?▾
Probability is a way of measuring how likely an event is to happen, written as a number from 0 to 1. A probability of 0 means the event is impossible, and 1 means it is certain. In Class 9 it is mostly found from the results of repeated experiments.
How do you calculate empirical probability?▾
Empirical probability is found from actual experiments. Divide the number of times the favourable event happened by the total number of trials. For example, if heads appears 47 times in 100 coin tosses, the empirical probability of heads is 47/100 = 0.47.
What is the difference between an outcome and an event?▾
An outcome is a single possible result of an experiment, such as rolling a 3 on a die. An event is a group of one or more outcomes, such as rolling an even number, which includes the outcomes 2, 4, and 6.
Can probability be more than 1 or less than 0?▾
No. Probability is always between 0 and 1, including both. A value of 0 means the event cannot happen, and 1 means it is sure to happen. Any answer outside this range means a calculation error has been made.
What does it mean if the probability of an event is 0.5?▾
A probability of 0.5 means the event is equally likely to happen or not happen — there is a fifty-fifty chance. For example, getting heads on a fair coin has a probability close to 0.5 over many tosses.
How is empirical probability different from theoretical probability?▾
Empirical probability comes from actually performing trials and recording results, so it can vary with each set of experiments. Theoretical probability is calculated from reasoning about equally likely outcomes. As the number of trials grows, empirical probability tends to get closer to the theoretical value.
Disclaimer & Attribution
- All NCERT textbook PDFs displayed on this page are served directly from NCERT's official servers at ncert.nic.in. We do not host, store, or redistribute any PDF files on our servers.
- This website is free to use. We do not sell, charge for, or commercially exploit any NCERT content.
- All textbook content is the intellectual property of NCERT, Government of India and is published under their open-access policy for educational purposes.
- This page is provided purely for educational reference in compliance with NCERT's guidelines for non-commercial use of their freely available materials.