In Maths, we deal with a lot of numbers. For example, equations, integers, fractions and so on. But, looking at numbers all the time can get very confusing and tiresome. For this reason, sometimes we take the help of bar graphs, tables, charts etc to make sense of all these numbers. To begin with, let us learn about the bar graph. After that, let us understand how to create a bar graph.
Bar Graph Definition
A bar graph is a way to display data graphically by using rectangle bars. These bars are uniform in width but vary in height or length. Also, the length of each bar represents a value. In addition, the bars can be vertical or horizontal. Another name for vertical bars is columns. We use bar graphs to compare various items or choices. We also use them to show how something has changed over a period of time. They can also be used to show the frequency of certain data. Other names for bar graphs are bar charts or column graphs.
Here is a situation where you could use a bar graph. Suppose you want to find out which chocolate, A, B or C your classmates prefer the most. And so, you ask them to write down their preference. Once you have all the data, you make a frequency table. After calculating the frequency of each choice, you plot a bar graph. With just one look at the bar graph, you can tell which is the most preferred chocolate. This is the essence of a bar graph. It makes reading data extremely easy.
Browse more Topics under Data Handling
- Data and its Frequency Distribution
- Histogram and Pie-Charts
- Chance and Probability
- Arithmetic Mean
- Median and Mode
How to Make and Use a Bar Graph
- Collect data: The first step in drawing any graph is to collect data. Since bar graphs is a comparative study, make sure you collect data for all the categories.
- Draw the axis: In any graph, there are two axes. Draw the x-axis and the y-axis.
- Label the axis: First, label the x-axis. On the x-axis, we represent the categories. For example, we label the names of chocolates i.e. A, B, C on the x-axis. Next, label the y-axis. To do this, take the highest frequency and plot the points on the y-axis accordingly.
- Draw the Columns: Finally, we draw the bars. In general, the bars are not connected or continuous. Now, extend the bars from the base value to their corresponding frequency. And if the value falls between the plotted frequencies, take an approximate point between the two.
- Interpret the Data: Once the bar graph is complete, we can interpret it. We can find out the most and least preferred choices. We can also identify the outliers.
Advantages of a Bar Graph
- A bar graph diagrammatically represents data. This makes comparisons between different variables easy and convenient.
- They are actually the most popular method of displaying data because you can easily ascertain each separate frequency easily.
- Bar graphs are also the easiest diagram to prepare. They do not require too much effort
- Bar graphs are the most widely used method of data representation. They are in use in various industries, in retail, education and all sorts of businesses.
Solved Examples for You
Question 1: What is the ratio of the total sales of branch B2 for both years to the total sales of branch B4 for both years?
Answer : From the graph, the combined frequencies of B2 and B4 are
B2 = 75 + 65 = 140
B4 = 88 + 95 = 180
Therefore, ratio =140:180 = 7:9
Question 2: What are the use of bar graphs?
Answer: We use bar graphs to compare values between different groups or to track changes over time. Besides, bar graphs are the best option when you are measuring change over time, and when the changes are larger.
Question 3: What is a simple bar graph?
Answer: A simple bar graph or chart is a chart that we use to represent data involving only one variable classified on a spatial, temporal or quantitative basis. In addition, in a simple bar chart or graph, we make bars of equal width but their length varies according to the data.
Question 4: List the names of six types of graphs.
Answer: The six types of graphs are a line graph, bar graph, pictograph, histogram, area graph, and scatter plot. All these represent data but their presentation is different from one another.
Question 5: What is key in a bar graph?
Answer: A key in a chart provides information about the data sets displayed on the chart. Another name for a key is a legend. Furthermore, we can use keys in two different modes. The first mode is the horizontal mode. It is designed to sit in the margins of the chart. The second mode is a vertical one. It is designed to sit over the chart.