Mathematics · Class 9
Statistics
Mean, median, mode of grouped data and graphical representation.
3 sections15–25 min read6 MCQs · 2 examples
Chapter Overview
Statistics deals with collecting, organising, and interpreting data. Class 9 covers mean, median, mode of ungrouped data, graphical representation (bar graphs, histograms, frequency polygons), and measures of central tendency.
Measures of Central Tendency
Mean
x̄ = (sum of observations) / n
Median (odd n)
Middle value when data is arranged in order
Median (even n)
Average of two middle values
Mode
Value with highest frequency
Graphical Representation
- Bar graph: discrete data with gaps between bars
- Histogram: continuous data, no gaps, area ∝ frequency
- Frequency polygon: line graph joining midpoints of class intervals
- Ogive: cumulative frequency curve
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Example 1: Mean
Find mean of 4, 7, 8, 9, 12.
- 1Sum = 4 + 7 + 8 + 9 + 12 = 40
- 2n = 5
- 3Mean = 40/5 = 8
Answer
Mean = 8
Example 2: Median
Find median of 3, 1, 7, 5, 9.
- 1Arrange: 1, 3, 5, 7, 9
- 2Middle value (3rd of 5)
Answer
Median = 5
Key Points to Remember
- ✓ Mean uses all values; affected by extreme values
- ✓ Median better for skewed data
- ✓ A data set may have no mode or multiple modes
Exam Tips
- • Always arrange data before finding median
- • Label axes and scale on graphs
- • State n clearly in mean calculation
Practice MCQs — Statistics
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Question 1 of 6Score: 0/0
Mean of 2, 4, 6 is: