TOPICS

Formulae

Statistics

Median = l + [(n/2 - cf)/f] x h

(i) Direct Method: x = Σf_{i}x_{i}/Σf_{i}(ii) Assumed mean method: x = a + Σf_{i}d_{i}/Σf_{i}(iii) Step-deviation method: x = a + (Σf_{i}u_{i}/Σf_{i}) x h where a = assumed mean, Σf_{i}or n = number of observations, h = class size (assuming class size to be equal).

Mode = l + [(f_{1}- f_{0})/(2f_{1}- f_{0}- f_{2})] x h where l = lower limit of the modal class, h = size of the class interval (assuming all class sizes to be equal), f_{1}= frequency of the modal class, f_{0}= frequency of the class preceding the modal class, f_{2}= frequency of the class succeeding the modal class.

Median = l + [(n/2 - cf)/f] x h where l = lower limit of median class, n = number of observations, cf = cumulative frequency of class preceding the median class, f = frequency of median class, h = class size (assuming class size to be equal).

3 Median = Mode + 2 Mean

CLASSES