**Question: **Rice production (in Kg) of 20 acres for the 9 set of observations is : 1230, 1150, 1040, 2310, 1453, 1755, 1752, 1900, 1885.

Find the quartile deviation for the given data.

** Solution: **
Given n = 9

Quartile deviation (Q.D) is given by the formula

Quartile deviation = $\frac{Q_{3} - Q_{1}}{2}$

To find The first quartile ($Q_{1}$)

$Q_{1}$ = Value of ($\frac{n+1}{4}$) th item

Value of $\frac{9+1}{2}$ th item

So, it is the value of 5th item $Q_{1}$ = 1453.

$Q_{3}$ = Value of $\frac{3(n+1)}{4}$ th item

Value of (7.5) th item

7th item + 0.5 (8 th item - 7th item)

$Q_{3}$ = 1752 + 0.5 (1900 -1752) = 1826

Now, quartile deviation = $\frac{1826 - 1453}{2}$

Therefore, quartile deviation = 186.5