## Line Graphs - Reading and Interpreting

#### 1. What is a line graph?

A

It displays

**line graph**or a**line chart**is a type of chart.It displays

**data as points**which are connected to**show trends**.#### 2. Reading and Interpreting Line Graphs

The table below shows the number of cakes that a bakery sold last week.

The line graph below shows the information given in the table above.

The line graph tells us the following things:

The line graph below shows the information given in the table above.

The line graph tells us the following things:

- The bakery sold the least number of cakes on Tuesday (
*the*)**lowest point**is on Tuesday - The bakery sold the same number of cakes on Saturday and Sunday (
*both Saturday and Sunday are at the*)**same level** - The bakery sold the most number of cakes over the weekend (
*the*)**highest points**are on Saturday and Sunday - There was a decrease in the number of cakes sold from Monday to Tuesday (
*this is called a*)**dip**in the graph - After Tuesday, the number of cakes that the bakery sold increased each day till Saturday (
*this is known as an*)**upward trend**as the line goes up

#### 3. The following line graph shows Ria's height from birth to 30 years of age.

**a. What was Ria's height at the age of 10?**

**Find 10 years on the horizontal axis (Age scale).**

*Step 1:***Move up the red arrow until you meet the line graph. (Follow the red lines)**

*Step 2:***Next, move left until you meet the vertical axis (Height scale).**

*Step 3:***The reading on the Height scale will give you Ria's height at the age of 10.**

*Step 4:***Ria's height was 140 cm at the age of 10.**

*Answer:***b. What was Ria's height when she was 18 years old?**

Ria's height was 165 cm when she was 18 years old.(Follow the green lines)

**c. How many centimetres did she gain from the age of 8 to the age of 16?**

Height at the age of 8 = 130 cm

Height at the age of 16 = 160 cm

Increase in height = 160 cm − 130 cm = 30 cm

She gained

**30 cm**from the age of 8 to the age of 16.

**d. What does the flat line on the graph from the ages of 20 to 24 mean?**

It means that her height had stabilized at the age of 20, or in other words, there was no progress in height after the age of 20. Such a flat line on the graph is known as a

**plateau**.

#### 4. The graph below shows the price of different lengths of lace at a shop.

**a. Find the price of 200 cm of lace.**

$16

**b. Find the price of 25 cm of lace.**

$2 (Follow the red lines)

**c. Jane paid $8 for some lace. How many centimetres of lace did she buy?**

100 cm

**d. Jill paid $10 for some lace. How many centimetres of lace did she buy?**

**Find $10 on the vertical axis (Price scale).**

*Step 1:***Move right on the green arrow until you meet the line graph. (Follow the green lines)**

*Step 2:***Next, move down the green arrow until you meet the horizontal axis (Length scale).**

*Step 3:***The reading on the Length scale will give you the answer.**

*Step 4:***She bought**

*Answer:***125 cm**of lace.

**e. Ruby bought 150 cm of lace. Zuby bought 275 cm of lace.**

How much did they pay for the lace altogether?

How much did they pay for the lace altogether?

150 cm of lace costs $12.

275 cm of lace costs $22.

$12 + $22 = $34

They paid

**$34**for the lace altogether.

**f. Binu bought 250 cm of lace and gave $50 to the cashier.**

How much change must the cashier return to Binu?

How much change must the cashier return to Binu?

250 cm of lace costs $20.

$50 − $20 = $30

The cashier must return

**$30**to Binu.