Question

Find out the quartile deviation of daily wages (in Rs.) of 7 persons is given below:-
120, 70, 150, 100, 190, 170, 250​

Answer 1

70,100,120,150,170,190,250
Q1 = (7+1)/2 th item =100
Q3 = 3(7+1)/2 th item =190
Qd = 190-100 = 90

Answer 2

Quartile deviation of daily wages (in Rs.) of 7 persons is 45.

Quartile deviation

• It computes the deviation in the middle or near the average of a given dataset.
• It is calculated as :

Q.D. = (Q3-Q1)/2

where,

1. Q3 is the third quartile i.e. median of third half of the data set
2. Q1 is the first quartile i.e. median of first half of the dataset  
3. Q3-Q1 is interquartile range
4. Q2 is the median

In order to find Q3 and Q1 we have to first find Q2

Arrange the given data in ascending order

70,100, 120,150,170,190,250

Median = (n+1)/2 = (7+1)/2=4th term=150

Q1= (n +1)/4 = 8/4 = 2nd term = 100

Q3=3(n+1)/4 = 24/4=6th term=190

Q.D= (190-100)/2 =90/2=45