12-17 Proportions and Percents

Front

What is the constant of proportionality?

Back

The constant of proportionality is the ratio between two proportional quantities, represented as k = y/x.

Front

How do you calculate the percent of seats that are empty in a theater?

Back

To find the percent of empty seats, use the formula: (Number of empty seats / Total seats) x 100.

Front

If Sarah earns $20 a day and spends 30% of her earnings, how much does she spend?

Back

Sarah spends $6 on Monday.

Front

What is the formula to find the unit rate?

Back

The unit rate is found by dividing the total cost by the number of units, e.g., Cost per unit = Total Cost / Number of Units.

Front

How do you find the percent of a number?

Back

To find the percent of a number, multiply the number by the percent (in decimal form). For example, 30% of 20 is 20 x 0.30 = 6.

Front

What does it mean if two quantities are proportional?

Back

Two quantities are proportional if they maintain a constant ratio or relationship to each other.

Front

How can you express a ratio as a fraction?

Back

A ratio can be expressed as a fraction by placing the first quantity over the second quantity, e.g., a:b = a/b.

Front

What is the relationship between fractions and percents?

Back

Fractions can be converted to percents by multiplying the fraction by 100.

Front

If you buy 5 pounds of concrete for $40, what is the cost per pound?

Back

The cost per pound is $8.

Front

What is a proportion?

Back

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