Practical uses of ratios
Home learning focus
Today we’re looking at the ways ratios can be used in everyday life. Including sharing money, using maps and scale drawings.
This lesson includes:
- two videos
- two interactive activities
Dave and Lisa win £500 between them. They agree to divide the money in the ratio 2:3.
How much does each person receive?
The ratio 2:3 tells us that for every £2 that Dave receives, Lisa will receive £3.
In other words, the total amount, Dave will receive 2 parts and Lisa will receive 3 parts. This means that there are 5 parts in total.
£500 represents 5 parts. Therefore, £100 represents 1 part.
Dave receives 2 parts: 2 x £100 = £200
Lisa receives 3 parts: 3 x £100 = £300
Map scales can be written in ratios and tell us how many units of length on land, or sea, are equal to one unit of length on a map.
For example, if you are travelling from Manchester to Newcastle and need to know how far it is, it would be very difficult to work this out from a map if the map does not have a scale.
The scale of a map is 1:50,000. 1 cm on the map represents 50,000 cm.
To convert from cm to m, divide by 100.
50,000 cm ÷ 100 = 500 m
Each cm on the map is 500 m or 0.5 km.
Watch the video below and find out what happens if a map scale isn’t used properly.
Scale drawings and models
In a scale drawing or model, all dimensions have been reduced by the same proportion.
A model boat is made to a scale of 1:20. This scale can be applied to any units, so 1 mm measured on the model is 20 mm on the actual boat. 1 cm measured on the model is 20 cm on the actual boat.
Scale drawing video
Watch this video about making a scale drawing of a football pitch then have a go at making a scale drawing yourself!
Scale drawing activity
Using a tape measure, calculator, paper and pencil; make a scale drawing of a room in your house.
Add the table, chair, bed, even you and your pets - make sure to use the same scale for everything.
There's more to learn
Have a look at these other resources around the BBC and the web.