Answer:
IQR = 4
Step-by-step explanation:
The interquartile range is the difference between the upper quartile and the lower quartile.
The first step is to find the median of the data set.
The median is the middle value of the data arranged in ascending order.
Arranging the data in ascending order
1 , 3 , 3 , 5 , 6 , 6 , 7 , 7 , 7 , 8 , 9
↑ median is 6
The upper quartile is the middle value to the right of the median
7 , 7 , 7 , 8 , 9
↑ upper quartile is 7
The lower quartile is the middle value to the left of the median
1 , 3 , 3 , 5 , 6
↑ lower quartile is 3
Thus
Interquartile range = 7 - 3 = 4
