Classes Class -intervals. 27 5 54. In such case class width is equal to the difference between the lower limits of the first two classes.
The difference between the successive lower limits or upper.
Every class should hold same class width. In each of these classes the least number is called the lower class limit and the greatest number is called the upper class limit eg in 20-29 20 is the lower class limit and 29 is the upper class limit. Now the difference between the values of two consecutive class marks is 4 therefore we subract 42 2 from each class mark to get the lower limit of the corresponding class interval and add 5 to each class mark to get the upper limit. In such case class width is equal to the difference between the lower limits of the first two classes.