Chapter TwoThe mean, the variance,and the standard deviation1. The Mean and other Measures of Central TendencyThe arithmetic mean is the average of a set of numbers. It can besymbolised as M and its formula is: N ∑X ∑X Arithmetic Mean = M = i=1 = (2 :1) N NIt is the most important of three measures of central tendency.The other two are the median and the mode. The mode is definedsimply as the value which occurs most frequently. The median isthe value below which exactly fifty percent of cases fall, and abovewhich are exactly fifty percent of cases. It is the point which splitsthe set of scores into two equal parts.ProblemsFind the mean, mode and median of the following sets of scores. A. 1, 2, 2, 3, 4, 5, 6. B. 10, 11, 12, 14, 15, 15. C. 7, 7, 8, 8, 10, 10.