Question

Question 4
The width of each of five continuous classes in a frequency distribution is 5 and the lower class limit of the lowest class is 10. The upper class limit of the highest class is:

A) 15
B) 25
C) 35
D) 40

Answer 1

Let x and y be the upper and lower class limit of the frequency distribution.
Given, width of the class = 5
$\Rightarrow x-y=5\dots \left(i\right)$
Also, given lower class (y) = 10.
On putting y = 10 in (i), we get,
$x–10=5\Rightarrow x=15$
so, the upper class limit of the lowest class is 15.

Hence, the upper class limit of the highest class
$=\text{Number of continuous classes}\times \text{class width}+\text{lower class limit of the lowest class}$
$=5\times 5+10=25+10=35$
Hence, the upper class limit of the highest class is 35.

Alternate Method:
After finding the upper class limit of the lowest class, the five continuous classes in a frequency distribution with width 5 are 10 - 15, 15 - 20, 20 - 25, 25 - 30, and 30 - 35.
Hence, the upper limit of this class is 35.