Question

Where is the 1st quartile in this data set?

21, 19, 5, 19, 17, 32, 26, 8, 31, 9, 23, 18, 32, 18, 33

Answer 1

You can go to wolframalpha.com and type

{21, 19, 5, 19, 17, 32, 26, 8, 31, 9, 23, 18, 32, 18, 33}

Then click "more" under statistics.

For a definition and examples: http://www.mathsisfun.com/data/quartiles.html

Answer 2

The boxplot generator at the following link is also an option:
http://www.alcula.com/calculators/statistics/box-plot/

Answer 3

That is very nice @Directrix !