1. What are Line Graphs?
A line graph is used to compare two sets of data that are related in some way. Most commonly, a line graph is used to show how something changes over time, maybe over the course of a week, a year, or even longer.
Line graph shows how values shown on Y- axis changes as another value changes on X- axis
Line graphs use points that are connected by lines which allow values to be estimated along a line drawn through the points.
For example, a graph to show how the temperature of water increases with time when it is heated.
What was the temperature of the water after 4.5 min?
First take a look at the two axes and try to understand what these axes denote
Let us now draw a parallel line from the x- axis on the plotted line from 4.5 min.
Join the perpendicular line on the y-axis.
At 4.5 minutes the temperature was 56°C.
1.1. Example on Line graphs
Example:
On a summer day, Jack starts filling a paddling pool with water. The graph below shows the depth of water in the paddling pool over time.
At what time the water was 15 cm deep?
Solution:
Let us draw a parallel line from the Y- axis on the plotted line from 15cm. Join the perpendicular line on the X-axis. Water was 15 cm deep at 3.08 pm.
Example:
James cycled to his house for lunch and returned back to the office. The travel graph below shows his journey.
On the way he stopped to buy some snacks and then after some time he stopped to fill the gas.
At what time did he stop to buy snacks?
Solution:
The graph is constant for 30 min from 11:00 to 11:30
Hence he stopped at 11:00 for 30 mins.
