emathematics.net
Español
User: desconectar
 
Maths Exercices

Scale drawings and scale factors

A scale drawing is a drawing of a real object in which all the dimensions are proportional to the real object. A scale drawing can be larger or smaller than the object it represents. The scale is the ratio of the drawing size to the actual size of the object.

  • The ratio of the length of the scale drawing to the corresponding length of the actual object is called as scale factor.
  • The ratio of any two corresponding lengths in two similar geometric figures is called as scale factor.

On a map having a scale of 1 inch = 25 miles, the distance between two cities is 3.2 inches.  What is the actual distance between the two cities?

Let d = the actual distance between the cities.  Write and solve a proportion.  Use the scale written as a fraction.

 

                            1 × d = 25 × 3.2            Cross products
                                  d = 80                    Simplify.

The actual distance between the two cities is 80 miles.


Designers are creating a child-sized version of a doll’s dress.  If they use a scale of 10 inches = 1 inch and the doll’s dress has a length of 4.5 inches, what is the length of the child-sized dress?

Write a proportion using the scale.

 

                      10 × 4.5 = 1 × c                   Find the cross products.
                                 45 = c                         Multiply.

The child-sized dress is 45 inches long.




The length of a pole in a picture is 9 inches. The scale of the picture was given to be as 4 inches : 16 inches. What would be the actual length of the pole?

The actual length of the pole would be inches