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Lesson: Applied Arithmetic - 10

Introducing Rates

[Page 10 of 36]
A rate is a ratio that compares two different kinds of numbers, such as miles per hour or dollars per pound. A unit rate compares a quantity to its unit of measure. A unit price is a rate comparing the price of an item to its unit of measure.
The rate "miles per hour" gives distance traveled per unit of time. Problems using this type of rate can be solved using a proportion, or a formula.

Video Lesson - rates and Ratios

A rate is simply a ratio that compares distance over time, or amount over time, or cost over units.

In other words: or or

The key to solving most Rate problems is to set them up as proportions, convert units if necessary, and solve for the unknown value:

Solving Rates: The Textbook Approach

A waitress serves 3 diners every 5 minutes. At this rate, how many customers will she serve in one hour?

Set up a proportion.
 
Convert units.
 
Cross-multiply and solve.

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Video Lessons and 10 Fully Explained Grand Tests

Large number of solved practice MCQ with explanations. Video Lessons and 10 Fully explained Grand/Full Tests.