Proportional Ratios

Front

What is a proportional ratio?

Back

A proportional ratio is a relationship between two quantities where the ratio of one quantity to another remains constant. For example, if the ratio of apples to oranges is 2:3, then for every 2 apples, there are 3 oranges.

Front

How do you determine if two ratios are proportional?

Back

Two ratios are proportional if their cross products are equal. For example, for the ratios a/b and c/d, they are proportional if a*d = b*c.

Front

What is the formula for finding a missing value in a proportional relationship?

Back

The formula is: (a/b) = (c/d), where a and b are known values, and c is the known value while d is the missing value. You can solve for d by cross-multiplying.

Front

Give an example of a real-life situation that involves proportional ratios.

Back

A real-life example is cooking. If a recipe requires 2 cups of flour for every 3 cups of sugar, this is a proportional ratio. If you use 4 cups of flour, you would need 6 cups of sugar to maintain the same ratio.

Front

What is the relationship between proportional ratios and scale factors?

Back

Proportional ratios are used to determine scale factors in similar figures. If two shapes are similar, the ratio of their corresponding sides is constant, which is the scale factor.

Front

Define the term 'scale factor'.

Back

A scale factor is a number that scales, or multiplies, some quantity. In geometry, it is the ratio of the lengths of two corresponding sides of similar figures.

Front

If a map has a scale of 1:100, what does this mean?

Back

A scale of 1:100 means that 1 unit on the map represents 100 units in real life. For example, 1 cm on the map equals 100 cm in reality.

Front

What is a unit rate?

Back

A unit rate is a ratio that compares a quantity to one unit of another quantity. For example, if a car travels 300 miles in 5 hours, the unit rate is 60 miles per hour.

Front

How can you find the unit rate from a ratio?

Back

To find the unit rate from a ratio, divide the first quantity by the second quantity. For example, if the ratio is 50 miles in 2 hours, the unit rate is 50 ÷ 2 = 25 miles per hour.

Front

What is the difference between a ratio and a proportion?

Back

A ratio is a comparison of two quantities, while a proportion states that two ratios are equal. For example, 1:2 is a ratio, while 1:2 = 2:4 is a proportion.