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Question 1077813: Income (in Rands) of drivers during the week are 1080,2000,1540,1580,2500,1800,1580 find Quartile Deviation
Please correct me from my answering
Sol: step 1 rearrangement of numerical order
1080,1540,1580,1580,1800,2000,2500
Let x equal to number of count
x=7
x=7/2=3.5
1580 is the third value in Q1
1540 is the second value in Q1
Q1=(1540+1580)/2= 1560
Q1=1560
2000 is the second value in Q3
2500 is the third value in Q3
Q3=(2000+2500)/2=2250
Q3 = 2250
QD= (Q3-Q1)/2
= (2250-1560)/2
= 345
Therefore quartile deviation is 345 correct me if I am wrong
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! there is more than one definition for quartiles. Here, there is a median, so remove it and take the middle of the lower and upper three: that would be 1540 and 2000 for Q1 and Q3. Q2, the median is 1580.
Others take the number of items and divide by 4, so 7/4 would be 3/4 of the way from the first to the second.
I prefer taking the median of the lower half for Q1 and upper half for Q3. The way you are doing it is taking the median of the lower 4 and the median of the upper 2, and that would not be correct. Take the median of the distribution. Then take the median of that. This is always defensible.
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