Find inter quartile range, quartile deviation and coefficient of quartile deviation from the following data:

Explanation

First arrange the data in ascending order:

`Q_(1)`=Size of `((N+1)/(4))`th item=Size of `((7+1)/(4))`th item
=Size of 2nd item =18 marks
`Q_(3)`=Size of `3((N+1)/(4))`th item =Size of `3((7+1)/(4))`th item
=Size of 6th item =28 marks
Inter Quartile Range `=Q_(3)-Q_(1)=28-18=10`
Quartile Deviation `=(Q_(3)-Q_(1))/(2)=(28-18)/(2)=5`
Coefficient of Quartile Deviation`=(Q_(3)-Q_(1))/(Q_(3)+Q_(1))=(28-18)/(28+18)=(10)/(46)`
=0.217