请问四分之一中位数quartile到底怎么算的，大家帮我看看阿

Quartiles
Quartiles are values that divide a sample of data into four equal parts. They are commonly used to describe data sets.

First quartile (Q1)
25% of the data are less than or equal to this value.

Second quartile (Q2)
The median. 50% of the data are less than or equal to this value.

Third quartile (Q3)
75% of the data are less than or equal to this value.


For example, for the following data: 7, 9, 16, 36, 39, 45, 45, 46, 48, 51

· Q1 = 16

· Q2 (median) = 42

· Q3 = 46

The interquartile range is equal to the distance between the first and third quartiles (Q3-Q1); thus, it spans the middle 50% of the data.