RD Sharma Class 8 Solutions Chapter 23 - Classification and Tabulation of Data (Ex 23.1) Exercise 23.1

The term ‘Data’ refers to information. In Statistical investigations, the first step is to collect observations. An observer's numerical observations are not immediately and directly usable. That's why it's referred to as Raw Data. Consider the following list of marks (out of 100) earned by ten eighth-grade students in a test:

56, 86, 45, 75, 83, 61, 91, 84, 72, 53,

Each entry in the preceding list is a numerical fact referred to as an observation. Raw Data is a term used to describe a collection of observations gathered at the start.

Data Presentation

After gathering Data, the investigator must figure out how to condense it into tabular form to study its key features. This is termed as presentation of Data. The raw Data can be arranged in a variety of ways, including:

• Alphabetical order

• Descending order

• Ascending order

An array is a collection of raw Data organised in ascending or descending order of magnitude. Let the scores obtained by 10 students in Class VIII in a Class test, out of a possible 50, be as follows:

45, 35, 34, 24, 49, 40, 38, 27, 43, 26, 

This type of Data is referred to as Raw Data or Ungrouped Data.

Frequency Distribution

A Frequency table, also known as Frequency Distribution, is a way of presenting raw Data in a way that allows the information contained in the raw Data to be easily understood. Frequency Distributions are of two types:

• Discrete Frequency Distribution. 

• Continuous or grouped Frequency Distribution.

Discrete Frequency Distribution

The values of the variable are arranged individually in a Discrete Frequency Distribution. The number of times each value appears is represented by its Frequency.

The workers' weekly wages in rupees are listed below. Make a Discrete Frequency Distribution of the Data.

150, 200, 300, 150, 250, 250, 300, 150, 300, 200, 250, 300, 250, 150, 200, 250, 300, 150, 150, 200, 250, 300, 150, 300, 150, 200, 300, 150, 250, 200.

Continuous Frequency Distribution

Grouped Frequency Distribution is another name for Continuous Frequency Distribution.

Class intervals and respective Class frequencies are given in this format.

• Initially, determine the Data set's range.

• Next, divide the range by the number of the group in which you want your Data to be placed and rounded up.

• After that, create groups by using Class width.

• Lastly, calculate the Frequency of each group.

Consider the following scenario for daily maximum temperatures in ℃ in a city over 30 days.

20, 24, 18, 28, 30, 15, 23, 17, 27, 24, 18, 26, 27, 30, 23, 15, 17, 16, 15, 34, 33, 35, 24, 28, 30, 34, 31, 15, 16, 35.

• Minimum value= 15

• Maximum value= 35

• Range= 35-15= 20

• Number of Classes= say, 4

• Width of each Class= 5

Table depicting the temperature Frequency Distribution in a city over 30 days.