\(Q_1 = \frac{1}{4}\) (N + 1)th

\(\frac{1}{4} \times 12^{th}\) no.

= 3rd no (\(\cong\) 4)

\(Q_3 = \frac{3}{4}\)  (N + 1)th

= \(\frac{3}{4}\) x 12th no.

= 9th no. (\(\cong\) 12)

Hence, interquartile range

= \(Q_3 - Q_1\)

= 12 - 4

= 8