1. Ratio topic so far.. What is Ratio?
How to Simplify Ratio (normal, units, decimals)
How to find an unknown quantity in a given ratio

2. Finding an unknown quantity in a given Ratio
A fruit drink is made by mixing lemon squash with water in the ratio 4:5. How much water needs to be added to 28cl of lemon squash to make the drink?
SQUASH : WATER 4 : 5
28 ÷ 4
x 7
x 7
28cl :
35cl ?
Therefore, 35cl of water needs to be added to make the drink.
(b)
To make Grey paint, you need to mix White and Black together in a ratio of 3:2. How much White will you need if you’re using 18 litres of Black?
WHITE : BLACK 3 : 2
18 ÷ 2
x 9
x 9
27litres ? :
18litres
Therefore, 27litres of White needs to be mixed to make Squirrel Grey. 2

3. L.O. To be able to find an unknown quantity in a given ratio
It is the opposite of simplifying (so don’t simplify again – you must find the unknown quantity!)
Write the ratio in words in the correct order
Write the simplified ratio given under the words
Write the quantity that you know underneath the correct word & number
Find the quantity that you don’t know

4. How are ratios used in maps? Ratios are used in the scale of a map
Map Ratios
How are ratios used in maps?
Ratios are used in the scale of a map
The scale of a map is the ratio of the distance on the map, to the corresponding distance on the ground
MAP : ACTUAL
Example of Scales
1cm : 4 km or :

5. What does the scale look like on a map?
So this line represents 2 kilometres in real life

6. Or it might look like this………..
This means that 1cm on the map equals 10,000 cm in real life

7. 2.4cm
4cm
Scale  1cm ≡ 200km
What is the actual distance between Liverpool & Paris?
What is the actual distance between Copenhagen & Berlin?
800km
480km

8. Scale may be given in 2 ways
Units not given (1 : )
Units given (1cm ≡ 5km or 1cm : 5km)
If the ratio has no units, then this means that the numbers are of the same units!
What units are you most likely to use on a map?
On a map, we will most likely be dealing with centimetres, this means that 1cm corresponds to 500,000cm (5km) in real-life!

9. Find the real distance between
SCALE  1cm ≡ 2.5km
Find the real distance between
MOSTA and ZEBBUG
PEMBROKE and ZURRIEQ
SIGGIEWI and HAL QORMI
CIRKEWWA and NADUR
If the real distance between L-Imdina & Hamrun is 8.5km – what is the distance on the map

10. Did you meet today’s Learning Objective?