Question

Find the quartile deviation of $4,6,9,12,18,20,23,27,34,48$ and $53$

• A. $12.5$
• B. $13$
• C. $12$
• D. $11.5$

Answer 1

The correct option is A $12.5$

Given series of numbers is already arranged in ascending order.
Thus median is the centre value $=20$
First Quartile $Q_1$ will be the mid value of the observations to the left of $20$ which is $9$.
Similarly, Third Quartile $Q_3$ will be the mid value of the observations to the right of $20$ which is $34$.
And Quartile deviation will be $\frac{Q_3-Q_1}{2}=\frac{34-9}{2}=\frac{25}{2}=12.5$.