Pedagogy of Mathematics (Part II) - Statistics, Statistics, Maths, IX std Maths, Samacheerkalvi maths, II year B.Ed., Pedagogy, Mathematics, Collection of data, primary data, secondary data, getting the facts sorted out, measures of central tendency, arithmetic mean, assumed mean, Arithmetic mean - ungrouped frequency distribution, Arithmetic mean - grouped frequency distribution, direct method, assumed mean method, deviation method, special property of the arithmetic mean,