Handling Data - Creating and interpreting bar charts

Grade 3IGCSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Definition: A bar chart uses rectangular bars of different heights to show and compare data.

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Axes: The horizontal axis (x-axis) shows categories, and the vertical axis (y-axis) shows the frequency (how many).

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Scale: The numbers on the vertical axis. In Grade 3, scales usually go up in 1s, 2s, 5s, or 10s.

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Title and Labels: Every bar chart must have a title and labels for both axes to explain the data.

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Interpreting: Looking at the height of a bar to determine its value. The tallest bar is the 'most popular' or 'mode'.

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Gaps: In a standard bar chart for discrete data, there should be equal gaps between the bars.

📐Formulae

\text{Value} = \text{Height of the bar aligned to the vertical scale}

\text{Difference} = \text{Value of Bar A} - \text{Value of Bar B}

\text{Total Data} = \text{Sum of all bar heights}

💡Examples

Problem 1:

A bar chart shows 'Favorite Fruits'. The bar for 'Apples' reaches the number 8 and the bar for 'Bananas' reaches 5. How many more students chose Apples than Bananas?

Solution:

3 students

Explanation:

8 - 5 = 3

Problem 2:

A bar chart uses a scale that goes up in 2s (0, 2, 4, 6, 8...). If the bar for 'Cats' ends exactly halfway between 4 and 6, how many people chose Cats?

Solution:

5

Explanation:

On a scale of 2, the midpoint between two numbers represents the odd number in between. Halfway between 4 and 6 is 5.

Problem 3:

In a survey about pets, 4 people chose Fish, 10 chose Dogs, and 6 chose Rabbits. If you were to draw a bar chart, what would the total height of all bars combined be?

Solution:

20

Explanation:

4 + 10 + 6 = 20