Quick Revision Notes & Formula Sheet

Class: 6th Mathematics
Chapter: Data Handling
Board: MP Board (NCERT Curriculum)

### Concept 1: What is Data? (डेटा क्या है?)

Definition: Data is a collection of numbers or information gathered to answer a specific question or represent facts.
Example: Marks obtained by students in a Mathematics test, temperatures of different cities in a week.
Raw Data (कच्चा डेटा): The data collected in its original, unorganised form is called raw data.

To make sense of data, it needs to be organised.

Frequency (बारंबारता): The number of times a particular observation or value occurs in the data.
Tally Marks (टैली मार्क्स): A quick way to count and record data using vertical and diagonal lines.
- 1 is written as |
- 2 is written as ||
- 3 is written as |||
- 4 is written as ||||
- 5 is written as [Cancel with diagonal: ||||] (Every fifth mark is drawn diagonally across the first four).

Definition: A pictograph represents data through pictures or symbols of objects.
Key Point: Always check the Key/Legend of the pictograph, which tells you how many units a single picture represents (e.g., 🍎 = 10 apples).

Definition: A display of information using bars of uniform width, drawn with equal spacing between them on a horizontal or vertical axis. The heights or lengths of the bars represent the values (frequencies).
Key Features:
1. Axes: Two perpendicular lines—Horizontal axis ($X$-axis) and Vertical axis ($Y$-axis).
2. Scale: The ratio chosen to represent a larger number with a smaller length (e.g., $1\text{ unit length} = 5\text{ students}$).
3. Equal Spacing: The gap between consecutive bars must be uniform.

Always write the Scale: When drawing a bar graph or pictograph, clearly mention the scale chosen at the top right corner.
Label the Axes: Do not forget to label the $X$-axis and $Y$-axis (e.g., $X$-axis: Names of students, $Y$-axis: Marks obtained).
Neatness: Use a sharp pencil and a scale (ruler) for drawing bar graphs and tally tables.