Conversion graphs
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Explainer Video
Summary
Conversion graphs
In a nutshell
Conversion graphs are a tool to convert between units, like between measurements for example. To read them, you just need to know how to read a straight line graph.
Converting using a graph
procedure
| 1. | Given a conversion graph that converts between unit X on the -axis and unit Y on the -axis, decide whether you want to convert from X to Y or Y to X. |
| 2a. | If converting from X to Y, read the X value off the -axis and find the corresponding -coordinate on the graph. This is the Y value converted from the X value. |
| 2b. | If converting from Y to X, read the Y value off the -axis and find the corresponding -coordinate on the graph. This is the X value converted from the Y value. |
Converting currencies
An example of a conversion graph is given below. It shows the relationship between two currencies, pounds sterling and euros.
Example 1
Use the graph below to convert into euros.
You are converting from pounds to euros. Since pounds is on the -axis, go from up to the line, then across to read the in-line value on the -axis. This is approximately . Hence
is approximately
Example 2
Use the same currency conversion graph to convert into pounds sterling.
To convert from euros to pounds, start on the -axis, and find the corresponding -coordinate. Start at on the -axis, go across until you meet the line, then go down to see the value on the -axis that is in-line.
This is approximately , so
is about
Note: The word "approximately" is used because the exact point is not labelled on the axis, so it can be tricky to read the exact value.
Converting distances
Converting distances on a conversion graph works in the exact same way as converting currencies.
Example 3
The graph below shows conversions between miles and kilometres:
Find how many kilometres there are in five miles.
Go to five on the miles axis (the -axis) and trace across until you meet the straight line graph. Then trace down to the kilometres axis (the -axis). It reads approximately , so you have found that five miles is about eight kilometres.
The gradient
The gradient of the straight line in a conversion graph represents how to convert one of the -unit into -units. Namely, if the gradient is , then one of the -unit is of the -units.
FAQs - Frequently Asked Questions
How do you read a conversion graph?
Conversion graphs are read in the exact same way as normal graphs: correspond the x-coordinate to the y-coordinate.
What does the gradient of a conversion graph line represent?
The gradient of the straight line in a conversion graph represents how to convert one of the x-unit into y-units. Namely, if the gradient is m, then one of the x-unit is m of the y-units.
What are conversion graphs?
Conversion graphs give a way to convert between two things, like measurements for example. They are a tool to convert between units.