The progressive sum of frequencies from the last class to the lower boundary of particular class is called __________.
The Cumulative Frequency of a class-interval is the sum of frequencies of that class and the classes which ________________ it.
If the cumulative frequency at a particular class interval 30 -35 is 19 and the cumulative frequency at the next class -interval i.e 35-40 is 27 , the frequency at 35-40 is __________