Objective:

Students will find the actual length from a scale drawing (8-3)

Vocabulary

Scale drawing-a drawing that is similar but is either larger or smaller than the actual object.

Steps

Read the problem carefully. Write down the problem. Set up your proportions. Solve as you would proportions.

Examples

Suppose a dinosaur had a scale of 1 inch = 20 feet. If the length of the dinosaur on the drawing is 2 inches, what is the actual length?

L = actual length of dinosaur

ExamplesSuppose a dinosaur had a scale of 1 inch = 20 feet. If the

length of the dinosaur on the drawing is 2 inches, what is the actual length?

L = actual length of dinosaur

Scale length of draw. 1 in. actual length 20 ft.

ExamplesSuppose a dinosaur had a scale of 1 inch = 20 feet. If the

length of the dinosaur on the drawing is 2 inches, what is the actual length?

L = actual length of dinosaur

Scale Dinosaurlength of draw. 1 in. 2 in. length in draw. actual length 20 ft. L actual length

ExamplesSuppose a dinosaur had a scale of 1 inch = 20 feet. If the

length of the dinosaur on the drawing is 2 inches, what is the actual length?

L = actual length of dinosaur

Scale Dinosaurlength of draw. 1 in. 2 in. length in draw. actual length 20 ft. L actual length

1 x L = 20 x 2 Find the cross products

ExamplesSuppose a dinosaur had a scale of 1 inch = 20 feet. If the length of

the dinosaur on the drawing is 2 inches, what is the actual length?

L = actual length of dinosaur

Scale Dinosaurlength of draw. 1 in. 2 in. length in draw. actual length 20 ft. L actual length

1 x L = 20 x 2 Find the cross products

L = 40 Multiply

The actual length of the dinosaur was 40 ft. or 480 in.

Examples

Suppose a drawing of a dinosaur had a scale of 1 in. = 18 ft. If the height of the dinosaur at the hips is ½ in., what is the actual height at the hips?

h = actual height of the dinosaur at the hips

Examples

Suppose a drawing of a dinosaur had a scale of 1 in. = 18 ft. If the height of the dinosaur at the hips is ½ in., what is the actual height at the hips?

h = actual height of the dinosaur at the hips

Scale height of draw. 1 in. actual height 18 ft.

Examples

Suppose a drawing of a dinosaur had a scale of 1 in. = 18 ft. If the height of the dinosaur at the hips is ½ in., what is the actual height at the hips?

h = actual height of the dinosaur at the hips

Scale Dinosaurheight of draw. 1 in. 1/2 in. height in draw. actual height 18 ft. H actual height

Examples

Suppose a drawing of a dinosaur had a scale of 1 in. = 18 ft. If the height of the dinosaur at the hips is ½ in., what is the actual height at the hips?

h = actual height of the dinosaur at the hips

Scale Dinosaurheight of draw. 1 in. 1/2 in. height in draw. actual height 18 ft. H actual height

1 x h = 18 x ½ Find the cross products

Examples

Suppose a drawing of a dinosaur had a scale of 1 in. = 18 ft. If the height of the dinosaur at the hips is ½ in., what is the actual height at the hips?

h = actual height of the dinosaur at the hips

Scale Dinosaurheight of draw. 1 in. 1/2 in. height in draw. actual height 18 ft. H actual height

1 x h = 18 x ½ Find the cross products

h = 9 Multiply

The actual height of the dinosaur at the hips was 9 ft. or 108 in.

Examples

In 1936, a meat company first produced a vehicle shaped like a hot dog. The 1995 version of the vehicle is 8 ft. wide and 27 ft. long. If a scale model is built with a width of 4 in., what will be the length?

L = length of the model

Examples

In 1936, a meat company first produced a vehicle shaped like a hot dog. The 1995 version of the vehicle is 8 ft. wide and 27 ft. long. If a scale model is built with a width of 4 in., what will be the length?

L = length of the model

Modelwidth of model 4in. actual model 8ft.

Examples

In 1936, a meat company first produced a vehicle shaped like a hot dog. The 1995 version of the vehicle is 8 ft. wide and 27 ft. long. If a scale model is built with a width of 4 in., what will be the length?

L = length of the model

Model Actual Vehiclewidth of model 4in. L length of model actual model 8ft. 27ft. actual length

Examples

In 1936, a meat company first produced a vehicle shaped like a hot dog. The 1995 version of the vehicle is 8 ft. wide and 27 ft. long. If a scale model is built with a width of 4 in., what will be the length?

L = length of the model

Model Actual Vehiclewidth of model 4in. L length of model actual model 8ft. 27ft. actual length

4 x 27 = 8 x L Find the cross products

Examples

In 1936, a meat company first produced a vehicle shaped like a hot dog. The 1995 version of the vehicle is 8 ft. wide and 27 ft. long. If a scale model is built with a width of 4 in., what will be the length?

L = length of the model

Model Actual Vehiclewidth of model 4in. L length of model actual model 8ft. 27ft. actual length

4 x 27 = 8 x L Find the cross products

108 = 8L Multiply

Examples

In 1936, a meat company first produced a vehicle shaped like a hot dog. The 1995 version of the vehicle is 8 ft. wide and 27 ft. long. If a scale model is built with a width of 4 in., what will be the length?

L = length of the model

Model Actual Vehiclewidth of model 4in. L length of model actual model 8ft. 27ft. actual length

4 x 27 = 8 x L Find the cross products

108 = 8L Multiply

108 = 8L Divide 8 8

13.5 = L The length of the model is 13.5 in. or 1 1/8 ft.