Question

The median of $100$ observations grouped in classes of equal width is $25$. If the median class interval is $20-30$ and the number of observations less than $20$ is $45$, then the frequency of median class is :

• A. $20$
• B. $12$
• C. $10$
• D. $15$

Answer 1

The correct option is C $10$

We have
$N=100,F=45,l=20,h=10$ and Median = $25$
Let $f$ be the frequency of the median class
Then,
$Median=l+\frac{\frac{N}{2}-F}{f}\times h$
$\Rightarrow 25=20+\frac{50-40}{f}\times 100$
$\Rightarrow 5=\frac{50}{f}\Rightarrow f=10$