Find the inter-quartile range of 1, 3, 4, 5, 8, 9, 10, 11, 12, 14, 16

  • A 6
  • B 7
  • C 8
  • D 9
waec 2018mathematics

The correct answer is C. 8

\(Q_1 = \frac{1}{4}\) (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

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