Question

Marks of students of class VIII-B are distributed in the grouped frequency distribution table given below.

Class intervals (Marks)	Number of Students
0 - 20	25
20 - 30	35
30 - 60	27
60 - 75	13
75 - 82	24
82 - 94	12
94 - 100	4

What is the length of the bar in the histogram for the 5th class interval ?

• A. 20
• B. 12
• C. 20.6
• D. 24

Answer 1

The correct option is C 20.6

Class length is varying in this distribution, in such cases, frequency per unit class has to be calculated and histogram has to be constructed with respective heights. For our convenience, here the least class length is taken as unit class length.

$\text{Modified length}=\frac{\text{Frequency of class}}{\text{Length of that class}}\times \text{Least Class length}$

In our case i.e 5th class interval
class length = 82 - 75 = 7
Frequency = 24
Least class length = length of last class (94 - 100) = 100 - 94 =6
Modified length = $\frac{24}{7}\times 6$ = 20.6