Scale — Grade 6 Math, what it means and where it is taught
What one grid step is worth — and where the axis starts.
Taught in Grade 6 Math.
Where it is taught
Practise this idea
19 questions in the course bank use Scale, in Sampling, Inferences & Comparing Populations, Proportional Relationships, Proportional Reasoning with Scale Drawings, Dilations & Similarity, How to Write a Proof, Similarity & Proportionality. The first 8 are below; the rest are in those units.
Problem 1
A factory samples 80 items and finds 24 defective. Estimate the number of defective items in a batch of 1,500.
Worked answer
450
2480 = 0.30
0.30 × 1500 = 450
Problem 2
A recipe uses 3 cups of flour for 24 cookies. How much flour for 60 cookies?
Worked answer
7.5
324 = 18 cup per cookie
18 × 60 = 7.5 cups
Problem 3
A drawing uses scale 1 : 50. A line measures 6 cm. How long is the real object in cm?
Worked answer
300
6 × 50 = 300 cm, which is 3 m.
Problem 4
A 4 in by 6 in photo is enlarged by factor 3. How long is the longer side now?
Worked answer
18
6 × 3 = 18 in
Problem 5
Triangle ABC has sides 6, 8, 10. A similar triangle has shortest side 9. Find its perimeter.
Worked answer
36
k = 96 = 1.5
Sides become 9, 12, 15
Perimeter = 36. (Or 24 × 1.5 = 36.)
Problem 6
A model car is 112 scale. The real hood has area 3.6 m2. Find the model hood's area in m2.
Worked answer
0.025
3.6 ÷ 144 = 0.025 m2
Problem 7
Two similar figures have areas 25 cm2 and 64 cm2. The smaller has perimeter 20 cm. Find the larger perimeter.
Worked answer
32
k2 = 6425, so k = 85
Perimeter is a length, so it scales by k
20 × 85 = 32 cm
Problem 8
A drawing uses scale 1 : 250. A field is 300 m long. How long is it on the drawing, in cm?
Worked answer
120
300 m = 30,000 cm
30000 ÷ 250 = 120 cm