1. Why Graphs Are Useful
Graphs help turn numbers into pictures. A graph shows patterns, comparisons, and trends more clearly than a long list of numbers. This makes it easier to understand data quickly and notice important differences.
Different types of graphs are used depending on the nature of the data and what we want to compare.
2. Bar Graphs
A bar graph displays data using rectangular bars. The height or length of each bar shows the value it represents. Bar graphs are useful for comparing different categories.
2.1. When to Use a Bar Graph
Bar graphs are used when data is divided into separate groups, such as favourite fruits, scores in subjects, or types of transport used by people.
2.2. Example of a Bar Graph
Suppose the number of apples sold over four days is 5, 8, 6, and 9. A bar graph would show four bars, each bar’s height matching the quantity sold on that day, making trends easy to compare.
3. Histograms
A histogram looks similar to a bar graph but is used for continuous numerical data. Instead of separate categories, histograms group data into ranges (called intervals or classes). The bars touch each other because the data ranges are continuous.
3.1. When to Use a Histogram
Histograms are useful when data is measured over intervals, such as heights, marks, weights, or ages. They help show how data is spread out.
3.2. Example of a Histogram
If the heights of students are grouped into ranges like 140–150 cm, 150–160 cm, and 160–170 cm, a histogram will show bars for each range. The height of each bar tells how many values fall in that interval.
4. Pie Charts
A pie chart represents data as parts of a circle. Each slice of the circle shows how much that part contributes to the whole. Pie charts are good for showing percentages or proportions.
4.1. When to Use a Pie Chart
Pie charts are useful when showing how a whole is divided into parts, such as time spent on activities, market shares, or monthly expenses.
4.2. Example of a Pie Chart
If a person spends a day as 8 hours sleeping, 6 hours studying, 4 hours playing, and 6 hours on other activities, a pie chart shows these portions as slices, making the distribution easy to visualize.