# NCERT Solutions for Class 7 Maths Chapter 3 Exercise 3.4

NCERT Solutions for Class 7 Maths Chapter 3 Exercise 3.4 (Ex. 3.4) Data Handling in English Medium and Hindi Medium free to use online or download in PDF. Contents and solutions are based on the latest CBSE Syllabus 2021-2022 and based on new NCERT Books.

In class 7 math exercise 3.4, the concept of probability is introduced. This is an easy topic but important one not only in class 7 but higher classes also.## Class 7 Maths Chapter 3 Exercise 3.4 Solution

### CBSE NCERT Class 7 Maths Chapter 3 Exercise 3.4 Solution in Hindi and English Medium

Class: 7 | Mathematics |

Chapter: 3 | Data Handling |

Exercise: 3.4 | NCERT Book’s Solution |

### Class 7 Maths Chapter 3 Exercise 3.4 Solution in Videos

#### Probability

Probability means possibility. It is a branch of mathematics that deals with the occurrence of a random event. The value is expressed from zero to one. Probability has been introduced in Maths to predict how likely events are to happen.

##### Some Terms Related Probability

##### Experiment

An operation which can produce some well-defined outcomes, is called an experiment.

##### Random Experiment

An experiment. in which all possible outcomes are known and the exact outcome cannot be predicted in advance is called a random experiment.

##### Trial

By a trial, we mean performing a random experiment.

##### Outcome

The result obtained from an experiment is called an outcome.

##### Event

An event is a collection of some outcomes of the experiment. In other words, the possible outcomes of a trial are known as events.

##### Experiment 1:

###### Throwing a Coin:

Let us throw a coin and let it fall freely on the ground, resting on one of its faces. On the upper face it will show either a Head or a Tail. Thus, in throwing a coin, all possible outcomes are Head, Tail, i,e., {H,T}.

###### Experiment 2:

Throwing two coins: Clearly, in throwing two coins, all possible outcomes are two Heads, two Tails. Head on the first coin and Tail on the second, Tail on the first coin and Head on the second, i.e., {HH, TT, HT. TH}.

###### Experiment 3:

##### Throwing a Dice:

A dice is a solid cube having 6 face, each one of which is a square. We mark these faces as 1, 2, 3, 4, 5, 6 respectively.

Let us throw a dice and let it fall freely on the ground, resting on one of its faces.

Then, the number on the upper face is the outcome.

Thus, in throwing a dice, all possible outcomes are 1, 2, 3, 4, 5, 6.

##### Empirical Probability

Suppose we make n trials of an experiment. Then, the probability of occurrence of an event E is defined as

P(E) = number of trials in which E occurs/ total number of trials

### Class 7 Maths Exercise 3.4 Important Questions

##### How do you find the probability of a question?

Divide the number of events by the number of possible outcomes. This will give us the probability of a single event occurring. In the case of rolling a 3 on a die, the number of events is 1 (there’s only a single 3 on each die), and the number of outcomes is 6.

##### What are some real life examples of probability?

Real Life Examples of Probability:

(i) Weather Forecasting. Before planning for an outing or a picnic, we always check the (ii)weather forecast.

(iii) Batting Average in Cricket.

(iv) Politics.

(v) Flipping a coin or Dice.

(vi) Insurance.

(vii) Lottery Tickets.

(viii) Playing Cards.

##### What are the 5 rules of probability?

Basic Probability Rules:

(i) Probability Rule One (For any event A, 0 ≤ P(A) ≤ 1)

(ii) Probability Rule Two (The sum of the probabilities of all possible outcomes is 1)

(iii) Probability Rule Three (The Complement Rule)

(iv) Probabilities Involving Multiple Events.

(v) Probability Rule Four (Addition Rule for Disjoint Events)

(vi) Finding P (A and B) using Logic.

##### A coin is tossed 100 times and head is obtained 59 times. On tossing a coin at random. find the probability of getting (i) a head, (ii) a tail.

Total number of trials = 100.

Number of heads = 59.

Number of tails = (100 – 59) = 41.

(i) P (getting a head) = number of heads/ total number of trials = 59/ 100

(ii) P (getting a tail) = number of heads/ total number of trials = 41/ 100