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Central Tendency
Central Tendency is the tendency of the data to converge at some value.

Measures of Central Tendency
Measures Central Tendency are the numerical values representative of the data. These are mean, mode and median.

Arithmetic Mean
It is given by sum of all observations divide by total number of observations. Consider the observations 10,15,20,30,35.
Arithmetic mean = [10+15+20+30+35] / 5 = 19

Geometric Mean
It is given by nth root of product of all observations where n is total number of observations . Geometric mean of 2,2,2,8

is 4th root of 2.2.2.8 = 4th root of 64 = 4

Harmonic Mean
It is the reciprocal of the average of reciprocals of all observations.
Geometric mean of 2,2,2,8 is calculated as
Step I : [1/2 + 1/2 + 1/2 + 1/8 ] / 4 = 13/32
Step II : 1 / [ 13/32 ] = 32/13

Median
Observation that occupies the middle space when data is arranged in increasing order is called as median. Median of 10,15,20,30,35 is 20.

Mode
Mode is the most frequently occurring observation. Mode can be more than one. Mode of 100,200,200,500,600 is 200.