Smart Charts - Bar Graphs

A bar graph shows the number of students who like different sports. The scale is $1 \text{ cm} = 5 \text{ students}$. If the bar for 'Cricket' is $4 \text{ cm}$ tall and the bar for 'Football' is $3 \text{ cm}$ tall, find the total number of students who like these two sports.

Step 1: Calculate the number of students who like Cricket. $\text{Cricket students} = 4 \text{ cm} \times 5 = 20 \text{ students}$ Step 2: Calculate the number of students who like Football. $\text{Football students} = 3 \text{ cm} \times 5 = 15 \text{ students}$ Step 3: Find the total sum. $\text{Total} = 20 + 15 = 35 \text{ students}$

We use the scale factor to convert the visual height of the bars (in cm) into the actual number of students before adding them together.

In a class, the number of students who own pets are: Dog ($12$), Cat ($8$), and Fish ($4$). If you draw a bar graph with a scale of $1 \text{ unit} = 2 \text{ students}$, how many units high will the bar for 'Cat' be, and how many more students have Dogs than Fish?

Step 1: Find the height of the 'Cat' bar. $\text{Height} = \frac{\text{Number of Cats}}{\text{Scale}} = \frac{8}{2} = 4 \text{ units}$ Step 2: Calculate the difference between Dog owners and Fish owners. $\text{Difference} = 12 - 4 = 8 \text{ students}$

To find the height of a bar for a graph, divide the actual value by the scale. To find 'how many more', subtract the smaller value from the larger value.

$20 + 40 + 30 + 50 = 140$

First, calculate the value of each bar by multiplying the height by the scale ($10$): Monday: $2 \times 10 = 20$ Tuesday: $4 \times 10 = 40$ Wednesday: $3 \times 10 = 30$ Thursday: $5 \times 10 = 50$ Total = $20 + 40 + 30 + 50 = 140$ ice creams.

$16 - 8 = 8$

Identify the unit heights from the graph: Ravi = $2 \text{ units}$, Sonu = $4 \text{ units}$. Calculate the actual number of trees: Ravi: $2 \times 4 = 8$ trees. Sonu: $4 \times 4 = 16$ trees. Difference: $16 - 8 = 8$ trees.