Ratios

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This lesson was created as a part of the SMART website and is hosted by the Illinois Institute of Technology

Objectives:

• Understand the concept of comparing two quantities

• Compare and express a ratio

A ratio is a comparison of two separate but related quantities.  For example, a pet store has seven animals available.

Three are cats, and four are dogs.  These amounts can be compared several ways.  The ratios may also be written three ways.

• Cats to dogs:  3 to 4 or 3/4 or 3:4    There are three cats to four dogs.

• Dogs to cats:  4 to 3 or 4/3 or 4:3     There are four dogs to three cats.

• Cats to total animals:  3 to 7 or 3/7 or 3:7    There are three cats to all the animals.

• Dogs to total animals:  4 to 7 or 4/7 or 4:7    There are four cats to all the animals.

Some of the ratios look like fractions (which are rational numbers).  Like fractions, these ratios may be reduced to lower terms or raised to higher terms.  They are left in fraction form and not changed to mixed numbers.  If there are ten parakeets and six hamsters, the ratio is 10/6 or 5/3.

Activity 1

In Activity 1, you will compare the components of flags.
Go to:
http://www.africaguide.com/shop/flags.htm

There are fifty images of African flags.  Compare the elements of the flags to the total number of flags.

Go to Activity 1

Activity 2

In Activity 2, you will compare the ingredients use in a Coca Cola Chocolate Cake.
Go to
: http://recipes.robbiehaf.com/C/101.htm

Write a ratio to answer each question.

Go to Activity 2