Question

Calculate quartile deviation for the following data: 30,18, 23, 15, 11, 29, 37,42, 10, 21

• A. 9.5
• B. 10.25
• C. 11
• D. 12.75

Answer 1

Answer:

B. 10.25

Quartile deviation = (Q₃ - Q₁)/2

Q₃= the third quartile

Q₁ = first quartile

10,11,15,18,21,23,29,30,37,42

n = 10

Q₁ = (n +1)/4 = 11/2

= 2.75^{th term}

Q₃= 3(n+1)/4

$=3\times2.75$

=8.25^{th term}

Q₁ = 2.75^{th term}

= (11 + 15)/2 = 13

Q₃= 8.25^{th term}

= (30 + 37)/2

= 33.5

QD = ( 33.5 - 13)/2

= 10.25