Scale Factors & Proportions

Front

What is a scale factor?

Back

A scale factor is a number that scales, or multiplies, a quantity. It is used to determine the size of a model or drawing compared to the actual object.

Front

How do you calculate the actual size from a scale drawing?

Back

To find the actual size, multiply the dimensions of the scale drawing by the scale factor.

Front

If a scale drawing has a width of 28 inches and the scale factor is 1 inch = 1.5 feet, what is the actual width?

Back

42 feet (28 inches x 1.5 feet/inch = 42 feet).

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal.

Front

How do you solve a proportion?

Back

Cross-multiply the terms and then solve for the unknown variable.

Front

If 2 inches on a map represents 40 miles, what does 1 inch represent?

Back

20 miles (40 miles / 2 inches = 20 miles/inch).

Front

What is the formula to find the length of a scale model?

Back

Length of model = (Actual length) x (Scale factor).

Front

If a whale is 65 feet long and the scale is 2 in : 3 ft, what is the length of the model?

Back

43.33 inches.

Front

What does it mean if two quantities are in direct proportion?

Back

If one quantity increases, the other quantity increases at the same rate.

Front

If the distance between two cities on a map is 4.125 inches and the scale is 2 inches = 40 miles, what is the actual distance?

Back

82.5 miles.