Bar Graph Or Bar Charts - Data Handling

Bar Graph

Data can be represented in various forms through numbers, pictures, tables, graphics, etc. The most common form of graphical representation of data is through bar graphs. A bar graph or bar chart portrays a visual interpretation of data with the help of vertical or horizontal rectangular bars of equal width which are uniformly spaced with respect to each other, where the lengths of the bars are proportional to the data to be represented. Let us consider the following example to understand bar graph more closely:

In a school of 400 students, the percentage of attendance of students is represented by the following table. We’ll represent it through a bar graph.

Bar Graph Bar Graph

Each bar in the above example is of uniform width and the data which varies is represented on one of the axes. Another axis represents the measure of the variable data through the height of the bars. The heights or the lengths of the bars denote the value of the variable. These graphs are also used to compare certain quantities.

In this example, the attendance of the students is represented by the X- axes and their number on the Y- axes. The bars are of uniform width and the length of the bar is equal to the number of students. By observing the bar graph it can be concluded that the number of students with 60% attendance is 105, the number of students with 70% attendance is 199, the number of students with 80% attendance is 29 and the number of students with 90% attendance is 73. Thus a close observation of the bar chart makes the data representation simple and easy and therefore bar graph makes data organized, its analysis and interpretation simple.

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Practise This Question

The bar graph below gives the strength of 'section A' consecutively for 6 years since 2009, when it was Class 6, Sec. A. Each year, same students get promoted to next class. Also, some of the students get new admission and some of the students get transferred. So, the number of students varies accordingly.

How many students got admitted to the class at the start of session 2012 if nobody from the previous year batch took a transfer and 2 students were not promoted?