What is ratio 8 to 5 It is

What is ratio? 8 to 5 It is a way of writing and making a numerical comparison between two or more quantities 1: 2: 5: 4 3: 5

A way of looking at numerical data • Making numerical comparisons between ingredients in a recipe • Making numerical comparisons between a mixture of paint colours • Making numerical comparisons between a scale drawing of a room and the actual dimensions of a room

Ratio • It is pronounced as – ray show • It is usually written with a colon (: ) which is read as ‘to’ 3 to 2 is written as 3 : 2

An example of ratio If there are two boys and three girls in the room. The ratio of boys to girls in the room is two to three. boys to girls can be written in shorthand as boys : girls two to three can be written in shorthand as 2: 3

The order is important If there are two boys and three girls in the room. The ratio of girls to boys is. girls to boys can be written in shorthand as girls : boys three to two can be written in shorthand as 3: 2

Another example of ratio If there are two apples for every five grapes in the fruit basket. The ratio of apples to grapes is two to five. apples to grapes can be written in shorthand as apples : grapes two to five can be written in shorthand as 2: 5

Remember the order If there are two apples for every five grapes in the fruit basket. What is the ratio of grapes to apples?

Remember the order If there are two apples for every five grapes in the fruit basket. The ratio of grapes to apples is 5 to 2 or The ratio of grapes : apples is 5 : 2

Keeping the ratio proportional If there must always be two apples for every five grapes in your fruit basket. 2: 5 • if you have four apples in the basket there must be 10 grapes 4: 10 • If you have twenty grapes then there must be eight apples 8: 20

Keeping the ratio proportional These ratios are all the same 4: 10 2: 5 8: 20 The middle one is the simplest way of expressing the ratio and that is always the way you would choose to write a ratio

You can make a comparison of more than two quantities At the sweet shop, John bought some sweets. He bought 2 Twix, 3 Mars, 4 Dairy Milks. The ratio of Twix to Mars to Dairy Milks is 2 to 3 to 4 In shorthand – The ratio of Twix : Mars : Dairy Milks is 2: 3: 4

The order is important At the sweet shop, John bought some sweets He bought 2 Twix, 3 Mars, 4 Dairy Milks. What is the ratio of Mars to Twix to Dairy Milks ?

The order is important At the sweet shop, John bought some sweets He bought 2 Twix, 3 Mars, 4 Dairy Milks. What is the ratio of Mars to Twix to Dairy Milks ? The ratio of Mars : Twix : Dairy Milks is 3 : 2 : 4

Ratio from a table of values This is a result of a survey of how some children get to school Bus 4 Car 7 Cycle 2 Walk 5 Comparing two quantities What is the ratio of children walking to taking the bus to get to school?

Ratio from a table of values This is a result of a survey of how some children get to school Bus 4 Car 7 Cycle 2 Walk 5 What is the ratio of walking to taking the bus? The ratio is 5 : 4 Comparing two quantities

Ratio from a table of values This is a result of a survey of how some children get to school Bus 4 Car 7 Cycle 2 Walk 5 Comparing three quantities What is the ratio of getting to school by car to cycling to walking?

Ratio from a table of values This is a result of a survey of how some children get to school Bus 4 Car 7 Cycle 2 Walk 5 Comparing three quantities What is the ratio of getting to school by car to cycling to walking? The ratio is 7 : 2 : 5

Getting values from a Pictogram What is the ratio of prawn to bacon?

Getting values from a Pictogram What is the ratio of prawn to bacon? The ratio of prawn : bacon is 3 : 5

Simplifying a ratio What is the ratio of Ready Salted to Cheese and Onion?

Simplifying a ratio What is the ratio of Ready Salted to Cheese and Onion? The ratio is 6 : 2

Simplifying a ratio A ratio of 4 : 8 can be simplified to 2 : 4 which can be simplified to 1: 2 Can you see how?

Simplifying a ratio ÷ 2 4: 8 2: 4 ÷ 2 1: 2

Simplifying a ratio 9: 3 ÷ 3 3: 1

Simplifying a ratio 25 : 10 ÷ 5 5: 2

Simplifying a ratio Favourite Crisps The ratio of 6: 2 Looking at the ratio of Ready Salted to Cheese and Onion, can it be simplified?

Simplifying a ratio 6: 2 ÷ 2 3: 1

Simplifying a ratio where possible Favourite Crisps The ratio of 6: 2 The ratio of Ready Salted to Cheese and Onion, should be written as 3 : 1

Simplifying a ratio uses the same process as simplifying a fraction 8 : 10 12 : 20 16 : 24

When writing a ratio • You have to consider the order of the numbers • You also must simplify it as much as possible the way you would with a fraction – finding a common divisor

This table shows the colour of cars in a car park. Red Black Green Silver Blue Yellow 50 35 15 20 45 10 What is the ratio of red cars to black cars? Write it in simplest form.

What is the ratio of red cars to black cars? Write it in simplest form. Red Black Green Silver Blue Yellow 50 35 15 20 45 10 :

What is the ratio of red cars to black cars? Write it in simplest form. Red Black Green Silver Blue Yellow 50 35 15 20 45 10 : 50 : 35

What is the ratio of red cars to black cars? Write it in simplest form. Red Black Green Silver Blue Yellow 50 35 15 20 45 10 : ÷ 5 50 : 35 10 : 7

The colour of cars Red Black Green Silver Blue Yellow 50 35 15 20 45 10 What is the ratio of black to green to silver cars?

The colour of cars Red Black Green Silver Blue Yellow 50 35 15 20 45 10 What is the ratio of black to green to silver cars? : 35 : : 15 : 20 7 : 3 : 4 Keep the order Simplify

Drawings, Maps, Diagrams Sometimes a diagram is made with a note Not drawn to scale This means the drawing will not be in proportion but is only a rough sketch. You would not take a ruler and start measuring because it is not an accurate drawing

Scales on maps and drawings If a map or drawing shows a legend with scale 1 : 20 This means for every one unit on the map it is 20 units in real size. You could take measures of this drawing with a ruler.

The unit must be the same Scale of 1 : 20 1 mm on the map would actually be 20 mm or 2 cm 2 cm on the map would actually be 40 cm 1 inch on the map would actually be 20 inches

Scales on maps Sometimes the scale might be worded this way 2 cm : 1 m (where the units are included in the scale)

Scales on maps 2 cm : 1 m 2 cm on the map actually represents 1 metre actually 4 metres in real life would be represented by 8 cm on the scale What would 12 cm on the map represent in real life?

Scales on maps 2 cm : 1 km What would 12 cm on the map represent in real life?

Scales on maps 2 cm : 1 km What would 12 cm on the map represent in real life? 2 cm : 1 km × 6 12 cm : 6 km