Question

Find the frequency of the median class if the following information is known for a grouped data whose median is = 45:

Lower real limit = 25
Sum of frequencies = 100
Cumulative frequency above the median class = 30
And, Size of the class interval = 10.

• A. 15
• B. 25
• C. 10
• D. 20

Answer 1

The correct option is C 10

The formula for median of a grouped data is given by,
Median = LRL+$\left(\frac{\frac{N}{2}-f_c}{f_m}\right)$$\times$i,
where LRL stands for the lower real limit, $f_m$=frequency of median class, $f_c$=cumulative frequency above the median class and $i$=size of the class interval
Substituting the given values in the above equation, we get:
$45=25+\left[\frac{\frac{100}{2}-30}{f_m}\right]\times 10\Rightarrow 45=25+[\frac{20}{f_m}\times 10]\Rightarrow 45=25+\frac{200}{f_m}\Rightarrow \frac{200}{f_m}=20\Rightarrow f_m=\frac{200}{20}=10$

Or, the frequency of the median class = 10.