Question

In the data set below, what is the interquartile range?

7
1
5
5
9
Submit

Answer 1

5

Explanation:

The interquartile range is the difference between the upper quartile and the lower quartile.

First find the median.

The median is the middle value of the data set arranged in ascending order

1 5 5 7 9 ← data in ascending order

↑ median

The lower quartile is the middle value of the data to the left of the median. If there is not an exact middle then it the average of the values on either side of the middle.

1 5

↑ lower quartile =
`(1+5)/(2)` = 3

The upper quartile is the middle value of the data to the right of the median.

7 9

↑ upper quartile =
`(7+9)/(2)` = 8

Thus

interquartile range = 8 - 3 = 5