Measures of Central Tendency

x̄ = (x1 + x2 + x3 + ... + xn) / n = Σxi / n

Σxi = n x̄

Σfx / Σf

A + (Σfd / Σf)

A + (Σft / Σf) × i

Median = (n + 1) / 2 th term if n is odd

Median = average of n / 2 th term and (n / 2 + 1) th term if n is even

Q1 = (N / 4)th observation if N is even

Q1 = (N + 1) / 4 th observation if N is odd

Q3 = (3N / 4)th observation if N is even

Q3 = 3(N + 1) / 4 th observation if N is odd

Inter-quartile range = Q3 − Q1