Introduction to concepts of statistics

1. Statistics and Probability
• Class 8 Mathematics (CBSE/DAV)
• Prepared by: [Your Name]
• Subject: Mathematics

2. Learning Objectives
• • Understand data and its representation
• • Construct and interpret bar graphs and pie
charts
• • Calculate mean, median, and mode
• • Understand and calculate probability
through real-life examples

3. Introduction to Data and Statistics
• Statistics helps us collect, organize, and
interpret data.
• Examples: Survey of students’ favorite sport,
temperature records, test marks.

4. Types of Data
• • Raw Data – Unorganized data collected from
source
• • Grouped Data – Data organized in a
frequency table
• • Frequency – Number of times a value occurs

5. Steps in Data Handling
• 1. Collection of data
• 2. Organization of data
• 3. Representation using tables and graphs
• 4. Interpretation and analysis

6. Pictograph
• • Uses pictures or symbols to represent data.
• Example (from DAV Book):
• Number of books read by students in a week.
• 1 symbol = 2 books.

7. Bar Graph
• • Shows data using rectangular bars.
• Example: Marks scored by 5 students in a test.
• • Can be vertical or horizontal.

8. Double Bar Graph
• • Compares two related sets of data.
• Example: Marks of boys and girls in
Mathematics and Science.

9. Pie Chart (Circle Graph)
• • Represents data as parts of a circle.
• Example: Time spent in daily activities – study,
play, sleep.

10. Measures of Central Tendency
• Mean = Sum of observations ÷ Number of
observations
• Median = Middle value when data arranged in
order
• Mode = Most frequent observation

11. Example from DAV Book
• Marks obtained by 10 students: 12, 14, 10, 16,
18, 14, 10, 12, 16, 14
• Mean = 13.6
• Median = 14
• Mode = 14

12. Real-Life Applications
• • Weather forecasting uses statistics
• • Sports records and averages
• • Business sales analysis

13. Introduction to Probability
• Probability means the chance of an event
happening.
• Example: Getting a head on tossing a coin.

14. Key Terms
• Experiment – Action with outcomes
• Trial – Repetition of experiment
• Outcome – Result obtained
• Event – Desired result

15. Probability Formula
• Probability = (Number of favorable
outcomes) / (Total number of outcomes)
• Example: P(getting head) = 1/2

16. Examples
• • Tossing a coin – Probability of head = 1/2
• • Rolling a die – Probability of getting 3 = 1/6
• • Drawing a red card – 26/52 = 1/2

17. Activity / Quiz
• Q1: What is the mean of 10, 20, 30?
• Q2: Probability of getting an even number on
a die?
• Q3: Draw a bar graph for students' favorite
fruits.

18. Summary
• • Data can be represented through graphs and
charts.
• • Mean, median, and mode describe data.
• • Probability measures chance.
• • Both topics are used in daily life decisions.

19. Assessment
• 1. Construct a double bar graph using your
class data.
• 2. Find mean, median, and mode of marks in
Mathematics.
• 3. Find probability of getting tails when a coin
is tossed.

20. Thank You
• Reflect: Where do you see statistics and
probability in real life?
• (Weather, games, reports, etc.)