1. Using Ratios (Proportions) to Make Predictions
TEKS 6.3 A/C
Lesson 4 (3rd 6 Weeks)

2. Proportion Two equivalent ratios or rates EX: Are and
equivalent (proportional)?
Two equivalent ratios or rates
EX: Are and
equivalent (proportional)?
Two equivalent ratios or rates
EX: Are and
equivalent (proportional)?
Two equivalent ratios or rates
EX: Are and
equivalent (proportional)?
Two equivalent ratios or rates
EX: Are and
equivalent (proportional)? 3 3 3 3 3 6 6 6 6 6 9 9 9 9 9 18 18 18 18 18

3. Simplify both fractions.
Since both fractions can be simplified to the same fraction, the ratios are equal. 3 3 1 ÷ = 3 9 3 6 1 6 ÷ = 18 3 6

4. Therefore,
The proportion is read as 3 is to 9 as 6 is to 18. 3 6 = 9 18
is a proportion.

5. Proportions can be written in different ways, as long as the relationship between the numbers stays the same.
EX:
x 2
x 2 9 18 3 6 or = = 6 9 18 3
x 2
x 2 or or
÷ 2
÷ 2 18 9 6 3 = or = 6 3 18 9
÷ 2
÷ 2

6. All four of these proportions represent the same relationship. 18 9 6
x 2
x 2 9 18 3 6 or = = 6 9 18 3
x 2
x 2 or or
All four of these proportions represent the same relationship.
÷ 2
÷ 2 18 9 6 3 = or = 6 3 18 9
÷ 2
÷ 2

7. Using proportions to make predictions
In some situations a ratio can be used to predict how often a related event will happen.
The related event can be described with an equivalent ratio.
Use the proportion method from lesson 3 to solve such problems.

8. EX: If 6 limes cost 99 cents, how much do 42 limes cost?
Set up proportion.
(Sideways T chart [Ratio Table])
Label the terms
Solve for the unknown. 6 99 7
x 7 x
Limes 6 42 6 9 3 x
Cost
99¢
693¢
x 7
Work

9. EX: Liliana takes 4 breaths per 10 seconds during yoga
EX: Liliana takes 4 breaths per 10 seconds during yoga. At this rate, about how many breaths would Liliana take in 2 minutes of yoga?
2 mins. = 120 secs.
x 12
Breaths 48 b 4 10
120
Seconds
x 12

10. EX: Billy feeds his horse 3 bales of hay every 5 days
EX: Billy feeds his horse 3 bales of hay every 5 days. About how many bales will Billy’s horse need for 31 days?
x 6
hay 3 18 h
days 5 31
x 6