1. Introduction to Data Handling

Data handling is the process of collecting, organizing, representing, and interpreting data to draw meaningful conclusions. In Class 8, students learn about different ways to manage and analyze data using tables, graphs, and measures of central tendency.

2. Collection and Organization of Data

• Data can be collected through surveys, experiments, or observations.
• Organizing data in tables helps in easy analysis and comparison.
• Frequency distribution tables show how often each value occurs.

3. Graphical Representation of Data

• Bar Graph: Uses bars of equal width to represent data. The height of each bar shows the frequency or value.
• Double Bar Graph: Compares two sets of data using bars placed side by side.
• Histogram: Similar to a bar graph but used for continuous data, with no gaps between bars.
• Pie Chart: Represents data as sectors of a circle, showing the proportion of each category.
• Line Graph: Shows data changes over time by connecting points with lines.

4. Measures of Central Tendency

• Mean (Average): Sum of all values divided by the number of values.
• Median: The middle value when data is arranged in order.
• Mode: The value that appears most frequently in the data set.

5. Probability (Introduction)

• Probability is the measure of how likely an event is to occur.
• Probability of an event = Number of favourable outcomes / Total number of outcomes
• Probability values range from 0 (impossible) to 1 (certain).

6. Word Problems & Examples

7. Activities

• Collect data from classmates about their favorite fruit and represent it using a bar graph.
• Conduct a survey at home (e.g., number of books in each room) and organize the data in a table.
• Toss a coin 20 times and record the number of heads and tails. Calculate the probability of each outcome.

8. Common Mistakes

• Confusing mean, median, and mode.
• Incorrectly drawing or interpreting graphs.
• Not arranging data in order before finding the median.
• Forgetting that probability is always between 0 and 1.

9. Practice Exercises

1. The heights (in cm) of 7 students are: 140, 145, 150, 140, 155, 150, 145. Find the mode.
2. Draw a bar graph to show the number of books read by 5 friends: 3, 5, 2, 4, 6.
3. If a die is thrown once, what is the probability of getting an even number?
4. Arrange the following data in ascending order and find the median: 12, 15, 11, 14, 13.
5. From the data: 2, 4, 4, 5, 6, 6, 6, 7, 8, find the mean.

10. Summary

• Data handling involves collecting, organizing, representing, and interpreting data.
• Data can be represented using tables, bar graphs, histograms, pie charts, and line graphs.
• Mean, median, and mode are measures of central tendency.
• Probability measures the chance of an event occurring.