Question

Calculate the quartile deviation of the following data: 500, 630, 750, 300, 129, 357, 100, 110, 117

• A. 185.5
• B. 225.75
• C. 275.5
• D. 320.25

Answer 1

Answer:

B. 225.75

Quartile deviation = (Q₃ - Q₁)/2

Q₃= the third quartile

Q₁ = first quartile

Q₁ = (n+1)/4

= 10/4 = 2.5^{th term}

Q₃ = 3[(n +1)/4]

$= 3\times2.5$

= 7.5^{th term}

100, 110, 117, 129, 300, 357, 500, 630, 750

Q₁ = 2.5^{th term} = (110 + 117)/2 =113.5

Q₃ = 7.5^{th term} = (500 + 630)/2 = 565

QD = (565 - 113.5)/2

= 225.75