Quartiles are like 'medians' First get the median, then get the median of the lower half which is the lower quartile. Do the same for the upper half. Source(s) Wikipedia.
http://answers.yahoo.com/question/index?qid=200907...

See related link. Upper and lower quartiles are the 75 and 25% percentile measures.
http://wiki.answers.com/Q/How_do_you_find_upper_an...

use the chi square test
http://uk.answers.yahoo.com/question/index?qid=200...

Another great demonstration video by Steve. If you need a maths tutor visit: www.hometutoringonline.co.uk
http://www.encyclopedia.com/video/psALBCNC62Ihow...
