Explain the meaning of the following terms:

(i) variate

(ii) class-integral

(iii) class-size

(iv) class-mark

(v) frequency

(vi) class limits

(vii) true class limits.

(i) A name which takes different values is called variates. For example, the mark obtained by students of class IX in mathematics is variates.

(ii) In a grouped data, the groups are called class-intervals. For example, 0-5, 5-10, 10-15… are class intervals.

(iii) The difference between the true upper limit and the true lower limit of a class is called its class size. For example, the class size of the class-interval 10-15 is

(iv) The mid value of a class is called the class mark. For example, the mid value of the class 10-15 is

(v) The number of observation falling in a particular class is called the frequency of that class or class frequency. For example, if the number of students obtaining marks 60-70 in a particular subject is 60, then the frequency of the class 60-70 is 60.

(vi) Class limits are the boundaries of a class. The left boundary of a class is called the lower limit and the right boundary of a class is called the upper limit. For example, for the class interval 60-70 the lower limit is 60 and the upper limit is 70.

(vii) The class limits of a continuous grouped frequency distribution are called true class limits. For example, 5-10, 10-15, 15-20, 20-25, 25-30 are continuous class intervals, then the true lower and upper limits (class limits) of the class 15-20 are 15 and 20 respectively. If the classes are not continuous, then adjust the class intervals to form continuous grouped class intervals.