Question

In a frequency distribution, if the upper boundary of the class is 2 times the lower boundary of the class. What are the class mark and class length in terms of the lower limit?

• A. Class marks is 2 times of lower boundary and class length is equal to lower boundary.
• B. Class marks is 1.5 times of lower boundary and class length is 2 times of lower boundary.
• C. Class marks is 1.5 times of lower boundary and class length is equal to lower boundary.
• D. Class marks is equal to lower boundary and class length is 1.5 times of lower boundary.

Answer 1

The correct option is C Class marks is 1.5 times of lower boundary and class length is equal to lower boundary.

Let,
upper boundary = x
lower boundary = y
Given , x = 2y
$\text{Class marks}=\frac{\text{upper boundary + lower boundary}}{2}$

Class marks = $\frac{\text{x+y}}{2}$

= $\frac{\text{2y+y}}{2}$ = $\frac{\text{3y}}{2}$ = 1.5y = 1.5 times of lower boundary

Class length = upper boundary - lower boundary = x - y = 2y - y = y = lower boundary