Range The range is the simple method of studying dispersion. It is defined as difference between the value of the smallest item and the value of largest item included in the distribution. Range= L-S L= Largest Item S= Smallest Item Coefficient of Range = L-S/L+S Que 1. Calculate Range and its coefficient Sol Range= L-S L = 250 S = 160 Range = 250-160 = 90 Coefficient of Range = L-S/L+S = 250-160/250+160 = 90/410 = 0.22 Quartile Deviation Sol Arrange in ascending order Que 2 Que 3 Mean Deviation: The mean deviation is also known as the average deviation. It is the average difference between the items in a distribution and the median or mean of that series Que 1 Que 2 Que 3 Standard Deviation: The standard deviation concept was introduced by Karl Person in 1823. The standard devia