Question

Calculate quartile deviation and its coefficient from the following data:

Answer 1

`Q_(1)`=Size of `((N)/(4))th" item"`
=Size of `((86)/(4))th" item"`
=Size of 21.5th item
21.5th item lies in the class 32-34. Thus,
`Q_(3)=l_(1)+(3((N)/(4))-c.f.)/(f)xxi`
`=38+(3((86)/(4))-60)/(12)xx2`
`=38+(64.5-60)/(12)xx2=38+(4.5)/(12)xx2`
=38+0.75=38.75
Quartile Deviation (QD)`=(Q_(3)-Q_(1))/(2)`
`=(38.75-33.05)/(2)`
`=(5.7)/(2)=2.85`
Coefficient of QD` =(Q_(3)-Q_(1))/(Q_(3)+Q_(1))`
`=(38.75-33.05)/(38.75+..05)`
`=(5.7)/(71.8)=0.079`