Ratios and Rates

Front

What is a ratio?

Back

A ratio is a comparison of two quantities that shows the relative size of one quantity to another, often expressed as 'a to b' or a:b.

Front

What is a rate?

Back

A rate is a specific kind of ratio that compares two different units, such as speed (miles per hour) or price (cost per item).

Front

If there are 12 pencils per pack, how many packs are needed for 108 pencils?

Back

9 packs.

Front

How do you calculate the unit rate?

Back

To find the unit rate, divide the total quantity by the number of units. For example, if you spend $40 on 5 pounds of concrete, the unit rate is $40 ÷ 5 = $8 per pound.

Front

What is the unit cost of an item?

Back

The unit cost is the price of one unit of a product, calculated by dividing the total cost by the number of units.

Front

If a teacher grades 25 homework assignments in 20 minutes, what is the rate of grading per minute?

Back

The rate is 1.25 assignments per minute (25 assignments ÷ 20 minutes).

Front

If gas costs $31.20 for 15 gallons, what is the cost per gallon?

Back

The cost per gallon is $2.08 ($31.20 ÷ 15 gallons).

Front

How do you find the total cost from a unit rate?

Back

Multiply the unit rate by the total number of units. For example, if the unit rate is $8 per pound and you buy 5 pounds, the total cost is $8 × 5 = $40.

Front

What is the formula for calculating a ratio?

Back

The formula for calculating a ratio is: Ratio = Quantity A / Quantity B.

Front

If you buy 15 pizzas for $97.50, what is the cost per pizza?

Back

The cost per pizza is $6.50 ($97.50 ÷ 15 pizzas).