# Data Handling and Presentation

## Overview

In this chapter, students learn how to collect, organise, and present data using various methods. The focus is on interpreting and visualising data through tables, tally marks, pictographs, and bar graphs. The chapter also introduces frequency tables and highlights the importance of choosing appropriate scales and making visually effective, non-misleading representations.

## Key Topics Covered

### 1. What is Data?

* **Definition**: Data is a collection of facts, numbers, observations, or measurements that convey information.
* **Examples**: Favourite colours, weights of students, popular games, etc.
* **Need for Data Handling**: Helps make sense of large quantities of information by organising it clearly.

### 2. Collecting and Organising Data

* **Activity**: Navya and Naresh collect data on favourite games in their class.
* **Tool**: Tally marks are used for counting frequencies.
* **Importance**: Organising data helps in drawing conclusions like the most preferred item.

### 3. Ascending Order and Frequencies

* **Example**: Shoe sizes of students are arranged in ascending order to identify smallest/largest size, most frequent size, etc.
* **Benefit**: Sorting helps answer questions easily.

### 4. Tables and Tally Marks

* **Use**: Count occurrences of items (e.g. sweets preferred, tree types spotted).
* **Structure**: Each category is listed, and tally marks or numbers show frequency.

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### 5. Pictographs

* **Definition**: A pictograph uses pictures or symbols to represent data.
* **Key Concepts**:

* A scale is chosen (e.g., 1 picture = 10 students).
* Helpful for quick comparisons.
* **Example**: Modes of travel used by students, sleep duration habits, etc.
* **Challenges**: When data is large or not a multiple of the scale, pictographs may be harder to draw accurately.
* **Comparison**: Pictographs make data intuitive but require accurate scaling and labeling.

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### 6. Bar Graphs

* **Definition**: Bar graphs use bars of equal width to show data. The height or length of the bar represents the quantity.
* **Uses**:

* Compare frequencies (e.g., number of absent students, vehicle traffic, runs scored, monthly expenses).
* Helpful when pictographs are impractical due to large data.
* **Steps to Draw**:

1. Draw horizontal and vertical axes.
2. Label the categories and values.
3. Choose an appropriate scale.
4. Draw bars according to frequencies.

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### 7. Frequency Distribution Tables

* **Definition**: Tables that show how often each value occurs.
* **Example**: Wickets taken by a cricketer in matches.
* **Benefit**: Helps analyse trends and total counts.

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### 8. Artistic and Aesthetic Considerations

* **Focus**: Make graphs visually appealing without misleading viewers.
* **Examples**:

* Use of shapes (bars vs. triangles).
* Use of colour and layout.
* Horizontal vs. vertical bars based on data type (e.g., height vs. distance).
* **Infographics**: Enhanced visuals that mix images and data. Useful but must be handled carefully to avoid confusion or exaggeration.

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## New Terms and Simple Definitions

| Term | Definition |
| --------------- | -------------------------------------------------------------------------- |
| Data | A collection of facts or information. |
| Tally marks | Vertical lines used for quick counting; every 5th line crosses the others. |
| Frequency | Number of times a value appears in data. |
| Pictograph | A chart that uses pictures or symbols to represent data. |
| Bar Graph | A graph that uses bars of equal width to represent data values. |
| Scale | Value represented by one unit or symbol in a graph. |
| Infographic | A visual image like a chart or diagram used to present data. |
| Ascending order | Sorting data from smallest to largest. |
| Category | A group or type within data (e.g. sweets, modes of travel). |

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## Practice Questions

### 🟢 Easy (3)

1. **What is data?**
**Answer**: Data is a collection of facts or information.

2. **How many tally marks represent the number 7?**
**Answer**: |||| || (5 + 2)

3. **If one picture in a pictograph represents 5 books, how many books are shown with 3 pictures?**
**Answer**: 3 × 5 = 15 books

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### 🟡 Medium (2)

4. **Draw a bar graph to represent the number of fruits: Apple - 4, Mango - 6, Banana - 3**
**Answer**: Use vertical bars with height 4, 6, and 3 respectively. Label the fruits on X-axis and frequency on Y-axis.

5. **If the number of students absent in 8 classes are: 3, 5, 4, 2, 0, 1, 5, 7, which class had the most absentees?**
**Answer**: Class 8 (7 students)

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### 🔴 Difficult (3)

6. **A pictograph uses 1 symbol = 10 students. If there are 3 full symbols and 1 half symbol, how many students are shown?**
**Answer**: (3 × 10) + (1 × 5) = 35 students

7. **Convert the following data to a frequency table using tally marks: 2, 3, 2, 4, 3, 2, 4, 4, 3, 2.**
**Answer**:

| Number | Tally | Frequency | | | | |
| ------ | ----- | --------- | - | - | - | - |
| 2 | | | | | | 4 |
| 3 | | | | | 3 | |
| 4 | | | | | 3 | |

8. **Imran’s family spent: Rent-3000, Food-3400, Education-800. Choose a scale and draw a bar graph.**
**Answer**: Use scale 1 unit = ₹200. Bars: Rent - 15 units, Food - 17 units, Education - 4 units.

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### 🔵 Very Difficult (2)

9. **Smriti scored runs in 8 matches: 80, 50, 10, 100, 90, 0, 90, 50. Use a bar graph with scale 1 unit = 10 runs. Explain the choice of scale.**
**Answer**: Using 1 unit = 10 runs keeps the graph compact and easy to draw. Minimum is 0, max is 100.

10. **You are making an infographic comparing the tallest mountains. Why might using triangle shapes for mountains be misleading?**
**Answer**: Triangles may vary in width as well as height, misleading the viewer into thinking width implies greater height or size.

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