---
source: ncert
topic: statistics
class_level: class_8
chapter: ch5
difficulty: beginner
---

Class 8 | Ch5: Data Handling
GROUPED DATA AND FREQUENCY:
Class interval: range of values grouped together. e.g., 0-10, 10-20, 20-30.
Class width = upper limit - lower limit.
Frequency: number of observations in each class.
Cumulative frequency: sum of all frequencies up to that class.
HISTOGRAM: bar graph for continuous data (no gaps between bars).
CIRCLE GRAPH (PIE CHART):
Central angle for each component = (component value/total) × 360°.
Example: Wheat 40% → angle = 0.40×360 = 144°.
PROBABILITY:
Experiment: activity with outcomes (throwing die, tossing coin).
Event: collection of one or more outcomes.
P(event) = number of favourable outcomes / total number of outcomes.
P(sure event)=1. P(impossible event)=0. 0≤P(E)≤1.
P(E)+P(not E)=1. So P(not E)=1-P(E).
SOLVED EXAMPLES:
Example 1: Die thrown. Find P(number>4).
Favourable: 5,6 → 2 outcomes. Total=6. P=2/6=1/3.
Example 2: Pie chart for budget. Food=40%, Rent=25%, Education=20%, Others=15%.
Angles: Food=144°, Rent=90°, Education=72°, Others=54°. Total=360°.
Example 3: P(drawing red card from deck)=26/52=1/2.
P(face card)=12/52=3/13. P(ace)=4/52=1/13.
COMMON MISTAKES:
In histogram, class intervals must be continuous (no gaps).
P(E)+P(not E)=1 always. P(E) cannot be greater than 1 or negative.