Proportions and Percents

Front

What is a proportion?

Back

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

Front

How do you calculate a percent of a number?

Back

To find a percent of a number, multiply the number by the percent (as a decimal). For example, to find 20% of 50, calculate 50 * 0.20 = 10.

Front

What is the formula for finding the constant of proportionality?

Back

The constant of proportionality (k) can be found using the formula k = y/x, where y is the output and x is the input.

Front

What does it mean if a graph is proportional?

Back

A graph is proportional if it passes through the origin (0,0) and shows a constant rate of change.

Front

If 18 is 45% of a number, how do you find that number?

Back

To find the number, divide 18 by 0.45. The number is 40.

Front

What percent of 250 is 225?

Back

To find the percent, use the formula (part/whole) * 100. So, (225/250) * 100 = 90%.

Front

What is a scale model?

Back

A scale model is a physical representation of an object that maintains the proportions of the original object.

Front

If a model is built at a scale of 5 in:25 ft, what is the actual size of a 1.5 in window in the model?

Back

To find the actual size, set up a proportion: 5 in / 25 ft = 1.5 in / x ft. Solving gives x = 7.5 ft.

Front

What is the relationship between fractions and percents?

Back

Percents are a way to express fractions with a denominator of 100. For example, 25% is equivalent to 25/100.

Front

How do you convert a fraction to a percent?

Back

To convert a fraction to a percent, divide the numerator by the denominator and multiply by 100.