Answer:
arah is at a miniature exhibit. There is a model of a skyscraper. Underneath the model was a ratio. It said:
1 inch=30 feet.
If the model is 38 inches tall, how Sarah use this information to find the actual height of the skyscraper?
In this concept, you will learn how proportions are used to find actual and scale dimensions using a scale ratio.
Using Proportions to Find Dimensions
A scale is a ratio that shows the relationship between the representation of an object and the real measurement of an object. Toy makers use scale ratios to make models of cars and airplanes that are proportional to the real thing. Architects use scale drawings to plan the design of buildings.
A scale drawing is a drawing that is used to represent and object that is too large to be drawn in its actual dimensions. If a drawing is to scale, you can use proportions to determine the actual dimensions of the scale drawing.
Let’s look at a scale drawing of a sculpture. In the drawing, the sculpture is 4 inches tall. The scale is 1 inch : 4 feet. It scale can be written as
1 in4 ft
(Note: Inch is abbreviated “in.” or with the double prime mark, ″. Foot/feet is abbreviated “ft” or with the single prime mark, ′.)
A drawing with this scale tells you that 1 inch on paper is equal to 4 feet in real life. If the drawing is 4 inches tall, use the scale to find the actual height of the sculpture.
First, create a proportion using equivalent ratios. Remember to write the corresponding units in the numerator and in the denominator. The actual height of the sculpture is represented by the variable x.
1 in.4 ft.=4 in.x ft.
Then, cross multiply and simplify the equation to find the value of x.
xx==4(4)16
The sculpture will be 16 feet tall.
Let’s make a scale drawing. Use the scale 1′′=2′. Draw a room that is 8′×12′.
First, write a proportion to find the measurement of the width.
1′′2′=x′′8′
Next, cross multiply and simplify the equation to find the value of x.
2x2xx===1(8)84
The drawing will be 4
, the equation is:
