Question

How to know that a distrubution is individual series or discrete series?

Answer 1

Difference between an individual series and a discrete series.
Individual Series ;-
When the raw data is presented individually in the form of a series, it is called an individual series. In simple words, individual series is the arrangement of raw data individually. It gives numeric values for a specific situation. In an individual series items are shown singly.
For example, following are the marks of secured by the students in a class out of 100.
56, 77, 88, 49, 60, 92, 70, 81, 69, 51,
As we can see, in the above data, it is not clear that how many students got 56 marks or how many got 77 and so on.
Discrete Series :-
On the other hand, discrete gives data for each specific value of variable. The important thing in the discrete series is that, the variable involved in the series has integer values. Data are presented in a manner that exact measurement of items are clearly shown. 
For example, Given below is a table that shows the wages earned by 30 workers. 
Wages                  No. of Workers (Frequency)
 2500                                 7  
 3000                                 9
 4000                                 5
 4500                                 6    
 5000                                 3
From the above table, it is very clear that 7 workers are getting wages Rs. 2500, 9 workers are getting Rs. 3000 and so on.