The Q3 given a set of data, is a number for which 75% of the data is less than that number. The Q3 is the same as the median of the part of the data which is greater than the median. It is the same as 75th percentile. The Q3 is also referred to as the upper quartile, third quartile, high quartile and higher quartile.
“Third Quartile.” Mathwords, www.mathwords.com/t/third_quartile.htm.