Answer:
A scale drawing or floor plan is a representation of an actual object or space drawn in two-dimensions. For a floor plan, you can imagine that you are directly above the building looking down. The lines represent the walls of the building, and the space in between the lines represents the floor.
In order to find the actual dimensions from a floor plan, you can set up and solve a proportion. The scale given in the drawing is the first ratio. The unknown length and the scale length is the second ratio.
Let’s look at an example.
The floor plan below shows several classrooms at Craig’s school. The length of Classroom 2 in the floor plan is 2 inches. What is the actual length, in feet, of Classroom 2?
First, set up a proportion. The scale in the drawing says that
12′′=3′
, therefore the proportion is:
0.5 inches3 feet
Next, write the second ratio. You know the scale length is 2 inches. The unknown length is
x
. Make sure that the second ratio follows the form of the first ratio: inches over feet.
0.5 inches3 feet=2 inchesx feetThen, cross-multiply.
0.530.5x0.5x===2x2×36Then, divide both sides by 0.5 to solve for
x
.
0.5x0.5x0.5x===660.512The answer is 12.
The actual length of the classroom is 12 feet.
