Question

Calculate quartile deviation for the following data:
$30,18,23,15,11,29,37,42,10,21$

Answer 1

Arranged data is

$10,11,15,18,21,23,29,30,37,42$

$Q_1=$ Value of ${\left(\frac{n+1}{4}\right)}^{th}$ term $={2.75}^{th}$ Term.

$Q_1=$ $2^{nd}$ term +$0.75/(3^{rd}$ term-$2^{nd}$term)

$Q_1=$$11+0.75(15-11)=14$

$Q_3=$ Value of ${\left(\frac{3(n+1)}{4}\right)}^{th}$ term $={8.25}^{th}$ Term.

$Q_3=$$30+0.25(37-30)=31.75$

$Q.D=\frac{Q_3-Q_1}{2}=\frac{31.75-14}{2}=8.875$