Representing Ratios as Concrete Models &

Fractions

Lesson 2 3rd 6 WeeksTEKS 6.3B

Ratio

Comparison of 2 quantities

When forming a ratio it is very important to compare the correct numbers in the order the problem requires.

Represented with a model.

EX:

• The ratio 2 out of 5 can be represented with a model.

• Written using a colon or as a fraction.• EX:

2:5 or

52

• Written as a decimal

5 2.00.4

04/21/23

20-0

Types of Ratios

• Compare part of something to the whole . (This is most like a regular fraction.)

• Compare one part to another part.

• Compare all of something to all of something else. (whole to whole)

Differences between ratios & fractions

• A fraction’s denominator always tells you how a whole is divided into parts.

• With ratios, a denominator may tell you:– How a whole is divided; or– The number of parts in another whole; or– A different part of the whole than the

numerator describes (like the ratio of green marbles to red marbles in the same bag of marbles).

• Ratios also do not follow fractions rules when it comes to units.– A fraction compares things that have

the same units (like 5 pieces of pie compared to 12 pieces in a whole pie).

– A ratio may compare things with like units or with unlike units (like 25 miles to one gallon).

• Fractions can be added or subtracted.

• Ratios cannot be added or subtracted.

EX:

• 7 out of 10 boys ride a bike to school. Write this ratio as a decimal

»7 to 10 710

0.7

EX:

• What is the ratio of shaded to unshaded?

16 to 14

We can simplify our answer. Divide 16 and 14 by 2.

8 to 7

• What is the ratio of shaded to unshaded?