**Q.16. Define series. **

Ans. A series, as used statistics, may be defined as things or attributes of things arranged according to some logical order.

**Q.17. State one feature of inclusive series? **

Ans. Inclusive method does not exclude the upper class limit in a class interval and hence, both class limits are parts of the class interval.

**Q.18. What is an open-end series? **

Ans. In open-end series, either the lower limit of the first class interval or the upper limit of the last class interval is missing.

Q.19. Write one function of tally marks.

Ans. Tally marks keep quick track of numbers in groups of five.

**Q.20. What are the two ends of a class called? **

Ans. The two ends of a class are called class limits.

**Q.21. Give another name for class interval. **

Ans. Class width is another name for class interval.

**Q.22. Define range. **

Ans. Range is the difference between the largest and the smallest value of a variable.

**Q.23. Write a short note on â€˜rangeâ€™. **

Ans. Range is the difference between the largest and the smallest values of the variable. A large range indicates that the values of the variable are widely spread while a small range indicates that the values of the variable are narrowly spread. If the class intervals are equal then range is the product of the number of classes and class interval of a single class. Range = Number of Classes Ã— Class Interval

**Q.24. When is frequency distribution with unequal classes more appropriate? **

Ans. When the classes are to be formed in such a way that class marks coincide to a value around which the observations in a class tend to concentrate then it is more appropriate to use unequal class interval.

**Q.25. Why is there no class mark in a discrete frequency distribution? **

Ans. Frequency array is the classification of data related to discrete variables. A discrete variable takes only integral values, that is, it does not take any fractional value between two adjacent integral values. Thus, there are no classes in a frequency array. Absence of classes implies no class intervals. Since the classes are absent in a discrete frequency distribution, there is no class mark as well.

**Q.26. What is the principal objective of classification of data? **

Ans. The principal objective of classification of data is to capture and distinctively present the diverse features of data. It is not done in an arbitrary manner and hence, saves time and effort.