Scale Drawings and Scale Factors

This lesson covers how to compute actual lengths from a scale drawing using a scale factor. It includes examples and exercises on calculating the scale factor and applying it to find dimensions in scale drawings, such as the perimeter of a boat, the length of a path, and the height of a race car.

What is the first step in working with scale drawings?

• Calculate the scale factor

• Convert units to percentages

• Identify the original and scale drawing

• Measure the perimeter

How do you calculate the scale factor?

• Multiply the original length by 100

• Divide the length in the scale drawing by the original length and multiply by 100

• Add the lengths of the original and scale drawings

• Subtract the original length from the scale drawing length

What is the scale factor if the length in the scale drawing is 11 and the original is 4?

• 275%

• 225%

• 250%

• 300%

After finding the scale factor, what is the next step to find the size of the scale drawing?

• Add the scale factor to the original size

• Subtract the scale factor from the original size

• Multiply the scale factor by the original size

• Divide the original size by the scale factor

In Exercise 1, what is the length of the shorter path if the longer path is 32.4 units?

• 10.8 units

• 12.5 units

• 18.3 units

• 15.2 units

What is the scale factor if the length in the scale drawing is 39 and the original is 12?

• 300%

• 325%

• 350%

• 375%

How do you find the height in the scale drawing if the scale factor is 325% and the original height is 4 feet?

• Multiply 325% by 4

• Subtract 325% from 4

• Divide 325% by 4

• Add 325% to 4

What does a scale factor greater than 100% indicate?

• A decrease

• No change

• An enlargement

• A reduction

What is the final step in determining the new length in a scale drawing?

• Subtract the scale factor from the original length

• Multiply the original length by the scale factor

• Divide the original length by the scale factor

• Add the original length to the scale factor

What is the scale factor if the length in the scale drawing is 3.3 cm and the original is 2 cm?

• 185%

• 175%

• 165%

• 150%