# NCERT Solutions for Class 7 Maths Chapter 3 Exercise 3.1

NCERT Solutions for Class 7 Maths Chapter 3 Exercise 3.1 (Ex. 3.1) Data Handling updated for academic session 2020-2021 free to use online or download. Questions answers are done according to latest CBSE textbooks issued for year 2020-21.

In class 7 math exercise 3.1 we have to learn how to find range of the given data and how to find mean of the tabular data. All the questions are easy but need more calculation.## Class 7 Maths Chapter 3 Exercise 3.1 Solution

Class: 7 | Mathematics |

Chapter: 3 | Data Handling |

Exercise: 3.1 | Hindi and English Medium Solution |

### CBSE NCERT Class 7 Maths Chapter 3 Exercise 3.1 Solution in Hindi and English Medium

### Class 7 Maths Chapter 3 Exercise 3.1 Solution in Videos

#### Data

A collection of numerical figures giving some particular type of information is called data.

Example:

The heights (in cm) of 11 players in a school are:

155, 148, 161, 144, 159, 152, 147, 163, 156, 150, 165.

We call it the data related to the heights of 11 players in a school.

##### Raw data

Data obtained in the original form is called raw data. Data given in each of the above examples is a raw data.

##### Array

Arranging the numerical figures of a data in ascending or descending order is called an array.

##### Tabulation of Data

Arranging the data in a systematic form in the form of a table is called tabulation of the data.

##### Observation

Each numerical figure in a data is called an observation.

##### Frequency of an observation

The number of times a particular observation occurs is called its frequency.

#### Statistics

It is the subject that deals with the collection, presentation, analysis and interpretation of numerical data.

##### Mean of Ungrouped Data

The mean of some given observations is defined as:

mean = sum of the given observations/number of the given observations

##### Find the mean of the numbers: 7.6, 6.8, 8.5, 9.4, 5.9, 6.4, 9.1 and 4.7.

Sum of the given numbers

= (7.6 + 6.8 + 8.5 + 9.4 + 5.9 + 6.4 + 9.1 + 4.7) = 58.4.

Number of the given numbers = 8.

So, mean = sum of the given numbers/ number of the given numbers

= 58.4/8 = 7.3

Hence, the mean of the given numbers is 7.3.

##### Mean of Tabulated Data

Let the frequencies of n observations x, x, x, …, x be frequencies f, f, f, …, f respectively. 1 2 3 n 1 2 3 n Then, we define:

Mean = (f1 x1 + f2 x2 + … + fn xn)/ (f1 + f2 + … + fn) = Σ(fi X xi)/ Σfi

where Σ (called sigma) is the Greek letter showing summation.

##### The following table shows the weights of 12 workers in a factory: Weight (in kg)/ (No. of workers): 60/ 4, 63/ 3, 66/ 2, 69/ 2, 72/ 1 Find the mean weight.

Mean weight = Σ(fi X xi)/ Σfi

Σxifi = 60 x 4 + 63 x 3 + 66 x 2 + 69 x 2 + 72 x 1

= 240 + 189 + 132 + 138 + 72 = 771

Σfi = 4 + 3 + 2 + 2 + 1 = 12

So, Mean weight = Σ(fi X xi)/ Σfi = 771/ 12 = 64.250 kg

Hence, the mean weight is 64.250 kg.

##### How many types of data handling are there?

Types Of Data: Data Handling In Maths.

Data or observations are classified into mainly two types:

(i) Qualitative data is descriptive information,

(ii) Quantitative data is numerical information.

Furthermore, we can divide quantitative data into two sections, like, continuous data and discrete data.

##### What does data handling include?

Data handling is the process of ensuring that research data is stored, archived or disposed of in a safe and secure manner during and after the conclusion of a research project. This includes the development of policies and procedures to manage data handled electronically as well as through non-electronic means.

##### What are the steps of data handling?

Six stages of data processing are:

(i) Data collection: Collecting data is the first step in data processing. …

(ii) Data preparation: Once the data is collected, it then enters the data preparation stage. …

(iii) Data input.

(iv) Processing.

(v) Data output/interpretation.

(vi) Data storage.