Find `Q_(3)` for the data 8, 13, 18, 9, 20, 11.

Explanation

Arranging the data in ascending order, we have 8, 9, 11, 13, 18, 20.
Here n = 6 (even)
`" " therefore Q_(3) = 3((n)/(4))"th observation" = 4(1)/(2)"th observation"`
`" " rArr Q_(3) = 4"th observation" + (1)/(2)"(5th observation - 4th observation)"`
`" " = 13 + (1)/(2)(18-13)" "therefore Q_(3) = 15.5`.