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Smart Charts - Pictographs and Bar Charts

Grade 3CBSE

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

🔑Concepts

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Data Collection: Data is a collection of facts or information, such as numbers, colors, or names, gathered by counting or observing. To make data easy to read, we organize it into charts or tables.

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Tally Marks: Tally marks are a quick way to count items in groups of 55. We draw four vertical lines ∣∣∣∣|||| for the first four items and a diagonal line across them for the fifth item to create a 'bundle' representing 55. This visual grouping helps in counting large numbers quickly.

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Pictograph: A pictograph is a chart that uses pictures or symbols to represent data. For example, a picture of a pencil could represent 1010 pencils. It helps us compare different quantities visually through the number of symbols shown.

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The Scale or Key: Every pictograph has a 'Key' which explains the value of one symbol. If the key says 11 flower symbol == 22 flowers, then seeing 55 flower symbols means there are 5×2=105 \times 2 = 10 flowers in total.

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Bar Chart: A bar chart represents data using solid rectangular bars of equal width. These bars can be vertical (standing up like towers) or horizontal (lying down like tracks). The height or length of the bar shows the value it represents.

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Axes in Bar Charts: A bar chart has two main lines. The horizontal line at the bottom is the xx-axis (usually showing labels like 'Monday, Tuesday'), and the vertical line on the side is the yy-axis (showing the number scale). They meet at a corner called the origin.

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Interpreting Charts: To understand a chart, we look for the tallest bar or the row with the most symbols to find the 'maximum' (most popular), and the shortest bar or fewest symbols to find the 'minimum' (least popular).

📐Formulae

Total Value=Number of Symbols×Value of each Symbol\text{Total Value} = \text{Number of Symbols} \times \text{Value of each Symbol}

Difference=Highest Value−Lowest Value\text{Difference} = \text{Highest Value} - \text{Lowest Value}

Total Items=Value of Group A+Value of Group B+…\text{Total Items} = \text{Value of Group A} + \text{Value of Group B} + \dots

💡Examples

Problem 1:

In a pictograph, a symbol of a star represents 44 points. If Rohan has 77 star symbols next to his name, how many points did he score?

Solution:

Step 1: Identify the value of one symbol from the key. 1 star=4 points1 \text{ star} = 4 \text{ points}. \ Step 2: Count the total number of stars Rohan has, which is 77. \ Step 3: Multiply the number of symbols by the value per symbol: 7×4=287 \times 4 = 28.

Explanation:

To find the total points, we use the scale provided in the key and multiply it by the count of symbols visible on the chart.

Problem 2:

A bar chart shows that 2525 students like Mango and 1212 students like Apple. How many more students like Mango than Apple?

Solution:

Step 1: Find the value for Mango, which is 2525. \ Step 2: Find the value for Apple, which is 1212. \ Step 3: Subtract the smaller number from the larger number to find the difference: 25−12=1325 - 12 = 13.

Explanation:

The phrase 'how many more' tells us to find the difference between two categories. We look at the heights of the two bars and subtract the smaller value from the larger one.