# 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

# Learn

### Sharing money

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

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.

Example

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.

Example

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.

# Practise

## Activity 1

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.

## Activity 2

Sharing an amount worksheet

Have a go at this worksheet from Twinkl below on sharing an amount into a given ratio.