Question

Define the following using proper terms(class interval, frequency etc.) :

#bargraph
#histogram
#frequency polygon

Answer 1

class interval: for example to represent a large amount of data , we divide the data into divisions such as 20-29,30-39...... these groupings are known as a class interval.
frequency:t the number of students (for example) who have obtained certain marks . if 4students got 70 marks then 70 is the frequency of the 4.
bar graph: it is simply a bar with some gap between each of the bars . it is used to represent a normal data.
histogram:it is a graph without any gap between each of the bars and it also has to be represented by a kink as given in the pic.it is used for the continuous class intervals such as 30.5-35.5,35.5-40.5....... . there is another type of histogram for the noncontinuous class intervals. we actually make a table as given data :0-20,20-30 it is not continuous so write the frequency 7,10 and the width of the class (if in0-20 the gap between them is 20 that's why) now we do some calculations length of the rectangle : divide the frequency (7)by width of the class (20)×the minimum width of the class (10)=(3.5).
frequency polygon:it is simple , just draw it as a histogram and mark the middle point on the top of the bar . join all the points and join the two ends to the x axis.