Probability Class 9th Notes - Free NCERT Class 9 Maths Chapter 15 Notes

Updated on 21 Apr 2022, 01:23 PM IST

Probability class 9 notes:

The NCERT chapter on Probability is a numerical measure of the uncertainty of many phenomena. Its positive value might range from 0 to 1. The NCERT Class 9 Maths chapter 15 Notes provide a quick overview of the Probability chapter. In the Probability class 9 notes with some FAQs, the main topics covered are What is Probability, Experiment, Trial, Experimental Probability, Coin Tossing Experiment, Rolling of Dice Experiment, Sum of Probabilities of Favorable and Unfavorable Events, and Sum of Probabilities of Favorable and Unfavorable Events. Class 9 maths chapter 15 notes contain important formulas.. CBSE class 9 maths chapter 15 notes contain systematic explanations of topics using examples and exercises. Notes for class 9 maths chapter 15 includes FAQ’s or frequently asked questions about the chapter. These concepts can also be downloaded from Probability class 9 notes pdf download.

Also, students can refer,

NCERT Class 9 Maths Chapter 15 Notes

Probability

Probability is a statistic for calculating the likelihood of an event happening.

Although no event can be predicted with certainty, the idea of probability can be utilised to determine how likely it is that it will occur.

A probability of 0 indicates an improbable event, while a probability of 1 indicates a certain event.

Experiment
An experiment:

is any method that may be repeated indefinitely or any sequence of actions with a well-defined set of possible outcomes.
There can be only one or multiple possible outcomes.
The sample space is another name for it.

Trail

A trial is a single event that is performed to determine the outcome.
A sample space or experiment is a collection of all potential trials that result in a well-defined set of outcomes.

Experimental Probability
Experimental/Empirical Probability

The empirical probability of a possible event is given by:

Probability of an event occurring

P(E) = Number of positive outcomes divided by the total number of outcomes

Coin Tossing Experiment

Take a look at a fair coin.

Heads or tails are the only two outcomes that can occur.
Number of possible outcomes = 2

Number of outcomes to get head = 1

The probability of getting head is equal to the number of outcomes to get head divided by the number of possible outcomes =1/2

Rolling of Dice Experiment

When a fair dice is rolled, the number that appears first is between one and six.

Assume we roll the dice once to see if three numbers would appear.

Number of possible outcomes = 6
Number of outcomes to get three = 1
The probability of getting three is equal to the number of outcomes to get three divided by the number of possible outcomes =1/6

Sum of Probabilities of Favorable And Unfavourable Events
When a trial is undertaken with the intention of reaching a specific result, the objective is more likely to be met.

A favorable occurrence is when something goes your way in a trial or event.

When a trial is done with the intention of reaching a specific outcome, there is a risk that the objective will not be accomplished.

A trial or incident like this is an unfavorable event.

All positive and negative event outcomes can be traced back to a well-defined set of circumstances.

Assume that an event has n positive outcomes in sample space S.

Then there are the S-n unfavorable results.

The chance of favorable and unfavorable results is determined by the number of trials completed. The aggregate of these probabilities, on the other hand, is always one.

Significance of NCERT class 9 maths chapter 15 notes

The notes for Probability class 9th notes will assist you in reviewing the chapter and gaining an understanding of the key concepts.

This NCERT class 9th maths chapter 15 maths notes will help students to understand the formulas, statements, and rules in detail.

These topics can be downloaded from class 9 maths chapter 15 notes pdf download to study offline.

NCERT solutions of class 9 subject wise

NCERT Class 9 Exemplar Solutions for Other Subjects:

NCERT Class 9 Notes Chapter wise

NCERT Class 9th Math Chapter 1 Notes

NCERT Class 9th Maths Chapter 2 Notes

NCERT Class 9th Maths Chapter 3 Notes

NCERT Class 9th Maths Chapter 4 Notes

NCERT Class 9th Maths Chapter 5 Notes

NCERT Class 9th Maths Chapter 6 Notes

NCERT Class 9th Maths Chapter 7 Notes

NCERT Class 9th Maths Chapter 8 Notes

NCERT Class 9th Maths Chapter 9 Notes

NCERT Class 9th Maths Chapter 10 Notes

NCERT Class 9th Maths Chapter 11 Notes

NCERT Class 9th Maths Chapter 12 Notes

NCERT Class 9th Maths Chapter 13 Notes

NCERT Class 9th Maths Chapter 14 Notes

NCERT Class 9th Maths Chapter 15 Notes

Articles

Simultala Awasiya Vidyalaya SAV Admission 2026 – Apply for Class 6, 9 & 11

Sep 23, 2025

DU BA LLB Eligibility Criteria 2026 - Age Limit, Qualifications, Marks

Sep 22, 2025

DU LLB Counselling 2026 – Seat Allotment, Documents, Admission Process

Sep 21, 2025

CGPA Calculator - Know How to Calculate CGPA

Sep 19, 2025

Upcoming School Exams

National Means Cum-Merit Scholarship

Ongoing Dates

NMMS Application Date

25 Jul'25 - 30 Sep'25 (Online)

Uttar Pradesh Board 12th Examination

Ongoing Dates

UP Board 12th Others

10 Aug'25 - 27 Sep'25 (Online)

Mock Test

Exam Pattern

Result

Uttar Pradesh Board 10th examination

Ongoing Dates

UP Board 10th Others

10 Aug'25 - 27 Sep'25 (Online)

Popular Questions

A block of mass 0.50 kg is moving with a speed of 2.00 ms^-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1) $0.34\; J$	Option 2) $0.16\; J$
Option 3) $1.00\; J$	Option 4) $0.67\; J$

Read Complete Answer

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times. Assume that the potential energy lost each time he lowers the mass is dissipated. How much fat will he use up considering the work done only when the weight is lifted up ? Fat supplies 3.8×10⁷J of energy per kg which is converted to mechanical energy with a 20% efficiency rate. Take g = 9.8 ms⁻² :

Option 1)

2.45×10⁻³ kg

Option 2)

6.45×10⁻³ kg

Option 3)

9.89×10⁻³ kg

Option 4)

12.89×10⁻³ kg

Read Complete Answer

An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1) $2,000 \; J - 5,000\; J$	Option 2) $200 \, \, J - 500 \, \, J$
Option 3) $2\times 10^{5}J-3\times 10^{5}J$	Option 4) $20,000 \, \, J - 50,000 \, \, J$

Read Complete Answer

A particle is projected at 60⁰ to the horizontal with a kinetic energy $K$ . The kinetic energy at the highest point

Option 1) $K/2\,$	Option 2) $\; K\;$
Option 3) $zero\;$	Option 4) $K/4$

Read Complete Answer

In the reaction,

$2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}$

Option 1) $11.2\, L\, H_{2(g)}$ at STP is produced for every mole $HCL_{(aq)}$ consumed	Option 2) $6L\, HCl_{(aq)}$ is consumed for ever $3L\, H_{2(g)}$ produced
Option 3) $33.6 L\, H_{2(g)}$ is produced regardless of temperature and pressure for every mole Al that reacts	Option 4) $67.2\, L\, H_{2(g)}$ at STP is produced for every mole Al that reacts .

Read Complete Answer

How many moles of magnesium phosphate, $Mg_{3}(PO_{4})_{2}$ will contain 0.25 mole of oxygen atoms?

Option 1) 0.02	Option 2) 3.125 × 10^-2
Option 3) 1.25 × 10^-2	Option 4) 2.5 × 10^-2

Read Complete Answer

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1) decrease twice	Option 2) increase two fold
Option 3) remain unchanged	Option 4) be a function of the molecular mass of the substance.

Read Complete Answer

With increase of temperature, which of these changes?

Option 1) Molality	Option 2) Weight fraction of solute
Option 3) Fraction of solute present in water	Option 4) Mole fraction.

Read Complete Answer

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol^-1) is

Option 1) twice that in 60 g carbon	Option 2) 6.023 × 10²²
Option 3) half that in 8 g He	Option 4) 558.5 × 6.023 × 10²³

Read Complete Answer

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t²) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m² , the number of rotations made by the pulley before its direction of motion if reversed, is