Am I right about this - Inclusive - This basically means that suppose in the interval - x – y The range starts from x and ends after y, that is including all possible values of y. So if we have a class interval 5 – 10 which is inclusive, then it will include 10.9999999999999999999999999999999999.... When constructing classes off this, since all values in the range of value 10 are included in 5 – 10, the next class should start from 11 to include new values. If it starts form 10, it will be invalid since it will include repetition of data. 0 - 5 6 – 11 12 – 17 etc... Exclusive - For an interval - x – y if this interval is exclusive, it will mean that values in this class starts from x and ends before y, that is it contains all values in the range of the constant y – 1. So subtraction is exclusive. For example class 5 – 10 will include values till 9.999999999999999999999999999999999 When constructing classes using exclusive intervals, we need to do it such that all possible values of variables come into it. So construction of exclusive classes will be like - 0 - 5 5 – 10 10 – 15 The reason for including 10 in the next class is cause first class does not contain values in the domain 10.