Bar graphs are charts or graphical representations of certain data, quantities, or numbers. It consists of rectangular bars with variable heights. The height of each bar represents the value of the quantity it represents. Bar graphs are ideal for comparing numbers and data. Bar graphs have vertical and horizontal axes known as the x and y-axis, respectively.
For example, if you have to compare the heights of your classmates, a bar graph can be used.
In the above bar graph, the numbers on the side (X-axis) show the height in cm. The names of your classmates go along the bottom (Y-axis). The bar height is higher for the taller classmates and lower for the shorter classmates.
Similarly, a bar graph with horizontal bars looks like:
The X-axis here gives the names of different snacks, while the Y-axis represents the number of votes for each snack.
To prepare bar graphs, let us take an example. Assume different food items in different quantities, such as 4 chocolates, 6 pizzas, 3 burgers, and 8 tacos. These quantities can be represented as bars. To make a bar graph for this data, we will draw the horizontal axis (x-axis) and vertical axis (y-axis). You can also use graph paper for making the bar graph. Then, label the horizontal axis as “types of food” and the vertical axis as “number of food items.” Keep an equal amount of space between each bar. Now, as per the data, you have to make rectangular bars to create the bar graph. This is what the bar graph will look like:
From the bar graph, we can easily say that tacos are the most popular food item as the bar representing tacos is the tallest among all.
There is a difference in format between tally charts and bar graphs. While a bar graph is represented with bars graphically, a tally chart is a collection of frequencies that are counted and recorded.
This is a tally chart of favorite sports among school children. Have a look at it.
Now, we will represent the same data on a bar graph. This is what a bar graph of the same tally chart looks like:
Here are the properties of bar graphs:
1. From the following bar graph of fruits tasted by children, answer these questions:
a. Which fruit is the most favorite among everyone?
b. Which fruit has been voted the least favorite?
a) The tallest bar represents the most favorite fruit, and from the bar graph, we can see that the tallest bar corresponds to the banana fruit. Hence, bananas are the most favorite fruit of all.
b) The least favorite fruit in the bar graph is given by the shortest bar, which is the bar corresponding to the peach fruit. Hence, peaches are the least favorite fruit of all.
From the above bar graph, find out how many students enjoy games and painting, respectively.
In the bar graph, we can count the number of students who enjoy a particular activity.
The purple bar and the red bar represent the students who enjoy games and painting, respectively. Hence:
Number of students who enjoy games = 6
Number of students who enjoy painting = 4
3. Have a look at the following bar graph and answer the questions that follow.
a. How many days were cloudy?
b.How many days were sunny?
c. How many less windy days were there than rainy days?
Let’s have a look at the weather bar graph. Each colored bar represents different weather conditions. The blue bar represents cloudy days. Similarly, the yellow bar shows sunny days, the red bar shows windy days, the green bar represents rainy days, and the pink bar shows snowy days.
a) Number of cloudy days = 3
b) Number of sunny days = 5
c) Number of rainy days = 10, Number of windy days = 5, therefore the number of less windy days would be, 10 – 5 = 5 days
4. Have a look at the following tally chart and prepare a bar graph.
a. Which drink is most chosen by the people?
b. How many more people choose lemonade over water?
Let us prepare a bar graph for the given questions.
As per the tally chart, the number of people drinking water is 5, the number of people enjoying fruit punch is 2, the number of people enjoying lemonade is 9, and the number of people having iced tea is 8.
With this data, a bar graph can be drawn as shown, with four bars representing each drink. The length of each bar corresponds to the number of people who have a particular drink.
a. From the tally chart and the bar graph, we can see that the maximum number of people, 11, drink lemonade. Hence, the most chosen drink is lemonade.
b. As per the chart and graph, water is chosen by 5 people, and lemonade is chosen by 9 people. Thus, the number of people who choose lemonade over water is, 9 – 5 = 4 people.
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Bar graphs are used for comparing data between different groups. They help in keeping track of changes in data over time as well.
Bar graphs are classified into two types: