# NCERT Solutions for Class 9 Maths Chapter 15 Probability

NCERT Solutions for Class 9 Maths Chapter 15 Probability: Predictions are common in our life. Whether it will rain today, whether India will win the match etc. Predictions are based on experiments and observation. Suppose we are doing an experiment of tossing a coin 20 times then each toss is known as a trial and the possible outcomes of a toss are head and tail. If in a toss a tail has occurred we call that an event tail has occurred. In these NCERT Solutions for Class 9 Maths Chapter 15, we will study the concept of probability and how to find the value of probability.

If we toss a coin there are two outcomes which are head or tail. So we will tell the probability of getting a n event head is 0.5 and an event tail is 0.5. If we toss a die then there are six outcomes. The chance of getting an event 3 on die is 1/6, that is the probability of getting an event 3 is 1/6.

NCERT Solutions for Class 9 Maths gives the relation of the probability of an event as follows

$\\The \ empirical \ probability \ P(E) \ of \ an \ event \ E \ happening,\ \\P(E)=\frac{Number \ of \ trials \ in \ which \ the \ event \ happened}{The \ total \ number \ of \ trials}$

Suppose if we toss a coin 100 times the head occurred 42 times and tail occurred rest of the time.

Then the probability of head occurred:

$P(H)=\frac{42}{100}$

and the probability of tail occurred:

$P(T)=\frac{100-42}{100}=\frac{58}{100}$

and the total probability P(H)+P(T)=1. That is total probability is always equal to one. The probability cannot be greater than one. The Probability of an event lies between 0 and 1 including 0 and 1

Q) Suppose we toss a coin 10000 times and we obtained the probability of head as 0.48. What will be the probability of tail and how many times the tail occurred?

Solution: We know that total probability =1

0.48+P(tail)=1 which implies P(tail)=0.52

$\\P(tail)=\frac{number\ of\ times\ tails\ occurred}{total\ number \ of\ trials}\\0.52=\frac{number\ of\ times\ tails\ occurred}{10000}\\number\ of\ times\ tails\ occurred=10000\times0.52=5200$

The main topics of the chapter Probability of NCERT Solutions for Class 9 are

15.1 Introduction

15.2 Probability – an Experimental Approach

It is mandatory to solve all the questions of NCERT Solutions to familiarise with the concepts we have studied in this chapter and the continuation of NCERT Solutions for Class 9 Maths Chapter 15 we will study in our 10 th class Maths and also in all higher studies related to Maths.

## NCERT Solutions for Class 9 Maths - Chapter Wise

 Chapter No. Chapter Name Chapter 1 Number Systems Chapter 2 Polynomials Chapter 3 Coordinate Geometry Chapter 4 Linear Equations In Two Variables Chapter 5 Introduction to Euclid's Geometry Chapter 6 Lines And Angles Chapter 7 Triangles Chapter 8 Quadrilaterals Chapter 9 Areas of Parallelograms and Triangles Chapter 10 Circles Chapter 11 Constructions Chapter 12 Heron’s Formula Chapter 13 Surface Area and Volumes Chapter 14 Statistics