Learn the Class 9 Madhyamik Mathematics Statistics Formulas with easy explanations and solved examples. This page covers Class Boundaries, Class Mark (Mid Value), Frequency Density, and Percentage Frequency, for quick revision and exam preparation.
Chapter 11 – Statistics | Class 9 Flash Formula
Class Boundaries
Let d be the difference between two consecutive class limits.
(i) Lower Class Boundary = Lower Class Limit - \frac{d}{2}
(ii) Upper Class Boundary = Upper Class Limit + \frac{d}{2}
Example :
Class Interval = 20 – 29
Difference between consecutive class limits (d) = 1
Lower Class Boundary = 20 − 1/2 = 19.5
Upper Class Boundary = 29 + 1/2 = 29.5
Therefore, Class Boundary = 19.5 – 29.5
Mid Value
Class Mark = \frac{\text{Upper Class Limit}+\text{Lower Class Limit}}{2}
Example :
Class Interval = 20 – 29
Class Mark = 20 + 29\over2
= 49\over2
= 24.5
Frequency Density
Frequency Density = \frac{\text{Class Frequency}}{\text{Class Size}}
Example :
Class Frequency = 24
Class Size = 6
Frequency Density = 24\over6 = 4
Percentage Frequency
Percentage Frequency = \frac{\text{Class Frequency}}{\text{Total Frequency}} × 100%
Example :
Class Frequency = 18
Total Frequency = 60
Percentage Frequency = (18/60) × 100 = 30%
You have reached the end.