Scale Ratios

Interpreting Scale Diagrams

Reading Maps and Scale Diagrams is an important life skill. The key is

understanding ratios.• Every map or architectural drawing uses

scales or ratios. This means that they are an exact smaller version of the real thing.

• Without knowing the scale, a map or drawing cannot be interpreted.

Notice the scale of the map. With this kind of scale, you

can use a ruler and compare it to the scale, to find out

approximately how many miles or kilometers it is

from one place to another

Compare to the scale. Make an

estimate from the scale.

Measure with a ruler the distance from one place to

another

Using this method, estimate the distance from:

1. Grand Falls to Hartland

2. Boiestown to Doaktown

3. Saint John to Fredericton

4. Dalhousie to St. George

Sometimes we use the expression, “as

the crow flies” which means a

straight line. Find the distance “as the

crow flies.”

As a ratio, what is the scale of this diagram?

Using the scale of the house plan, calculate the area of each room.

Count the number of blocks in the bottom right bedroomSet up a ratio 4 :1 = 13 : ϰ

Rewrite as fractions and cross multiplyϰ = 3.25 m

Rewrite as a fraction and cross multiply.ϰ = 3.25 m

A = length x width A = 3.25 m x 3.25 mA = 10.5625 m2

The scale is 4 blocks : 1 meterSo 4:1

3.25 m

3.25 m

Now do the same for the length of the room4 : 1 = 13 : ϰ

Remember the scale is 4 blocks : 1 metre

1

4BM

Help with Lounge

Separate the lounge into two rectangles and then add the two.

Count the blocks across the room and set up a ratio using the scale

20 blocks

x

20

1

4

Cross Multiply

ϰ=5 m

ϰ=5 m

Now do the same for the length of the room

x

17

1

4

Cross Multiply

ϰ=4.25 m

ϰ=4.25 m

You have now found the length and width of this part of the room.Area = Length x Width Area = 5 m x 4.25 mArea = 21.25 m2

Area = 21.25 m2

B

M

M

B

Now do the same for this part of the lounge.Once you find the area, you add the two parts to find the total area of the room

12 blocks

13 blocks

x

12

1

4

x

13

1

4

Calculate the length and width of the room using ratios and use A=LxW

Then add the two parts of the room to get the area of the room.

Advanced Skills 1.If the walls are 1.3 meters

high, and you ignore doors and windows, how many cans of paint will it take to paint the three bedrooms if 4 litres of paint are required to cover 9m2? Remember that you cannot buy cans of paint smaller than 4 litres.

2.How much will it cost if a 4 litre can of paint costs $35.97?