Final answer:
The median of an ordered data set has 50% of observations below and above it, and is also known as the 50th percentile.
Step-by-step explanation:
In an ordered data set, the median has 50% of observations both below and above it. The median is a measure of central tendency that is defined as the middle value in a rank-ordered data set, separating the upper half from the lower half. When the data set has an odd number of observations, the median is the value in the exact middle. For an even number of observations, it is the average of the two middle values.
Percentiles are a way to divide the data set into 100 equal parts. The 50th percentile represents the median. Quartiles similarly segment the data: the first quartile (Q1) is the 25th percentile, and the third quartile (Q3) is the 75th percentile. The interquartile range (IQR) spans the middle 50 percent of data points, calculated by subtracting the first quartile from the third quartile.