Mathematics Grade 7 15 min

Scale drawings: word problems

Scale drawings: word problems

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Introduction & Learning Objectives

Learning Objectives Identify and interpret the scale of a drawing or model. Set up and solve proportions involving scale drawings. Calculate actual dimensions of objects given their scale drawing dimensions and the scale. Determine the dimensions for a scale drawing given the actual dimensions and the scale. Convert units of measurement accurately when solving scale drawing problems. Apply understanding of scale drawings to solve real-world word problems. Ever wondered how architects design huge buildings on small blueprints, or how mapmakers fit entire countries onto a single page? 🗺️ It's all thanks to scale drawings! In this lesson, you'll learn how to understand and use scale drawings to solve problems. We'll explore how ratios and proportions help us fin...
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Key Concepts & Vocabulary

TermDefinitionExample Scale DrawingA drawing that shows a real object with accurate sizes reduced or enlarged by a certain amount (a constant ratio).A map of your city is a scale drawing where distances are reduced proportionally. ScaleThe ratio that compares the dimensions on a drawing to the actual dimensions of the object. It tells you how much the object has been reduced or enlarged.A scale of '1 cm : 5 m' means 1 centimeter on the drawing represents 5 meters in real life. Scale FactorThe ratio of a length on a scale drawing to the corresponding length on the actual object, expressed without units. It's often written as a fraction or a ratio like 1:100.If the scale is 1 cm : 100 cm, the scale factor is 1/100 or 1:100. Actual DimensionThe true, real-life measurement of a...
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Core Formulas

Setting up a Proportion for Scale Drawings $\frac{\text{Drawing Dimension}}{\text{Actual Dimension}} = \frac{\text{Drawing Dimension}}{\text{Actual Dimension}}$ This rule helps you find an unknown dimension (either drawing or actual) when you know the scale and one other dimension. Ensure units are consistent within each ratio or converted before solving. Using Scale to Find Actual Dimension $\text{Actual Dimension} = \text{Drawing Dimension} \times \frac{\text{Actual Unit Value}}{\text{Drawing Unit Value}}$ (from the scale) If your scale is given as '1 unit on drawing : X actual units', you can multiply the drawing dimension by X to find the actual dimension. This is a direct application of the scale ratio. Using Scale to Find Drawing Dimension $\text{Drawin...

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Sample Practice Questions

Challenging
The linear scale of a model ship is 1:100. If the area of a deck on the model is 20 cm², what is the actual area of the deck in square meters?
A.2 m²
B.20 m²
C.200 m²
D.2000 m²
Challenging
A map has a scale of 1:25,000. The map is placed on a photocopier and reduced to 75% of its original size. What is the scale of the new, smaller map?
A.1:18,750
B.1:31,250
C.1:33,333
D.1:25,075
Challenging
On an architectural drawing, a 36-foot long wall is represented by a line that is 4.5 inches long. On the same drawing, a window is 1.5 inches wide. What is the actual width of the window in feet?
A.12 feet
B.8 feet
C.10 feet
D.9 feet

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