Page 184 - Math Course 1 (Book 1)

Proportions and Ratios

Mo. 6

Lesson 2 constant of proportionality

Proportional relationships can also be described
using equations of the form y = kx, where k is the
KEY CONCEPTS: constant. The constant ratio is called the constant of
1. Identify proportional and non-proportional proportionality.
relationships in tables and graphs.
2. Describe a proportional relationship using y
an equation.
y=kx

MO. 6 - L2a x

Relationships: Proportional &
Non-proportional

Vocabulary A-Z
Let us learn some vocabulary Let’s Begin

Identify Proportional Relationships
Proportional

Two quantities are proportional if they have a con- Examples
stant ratio or rate.

The number of laps Determine whether the set of numbers in the
completed by Tom is pattern forms a proportion.
proportional to the time.
Time (min) Baseball 1 2 3 4
1 2 3 4 5
Cost(dollar) 2 3 4 5
Number of Tom 3 6 9 12 15
Laps
Completed Jane 4 6 8 10 12 1 = 2 = 3 = 4
2 3 4 5

Nonpropotional Answer NO

Relationships in which the ratios or rates are not
constant are said to be nonpropotional.
Determine whether the set of numbers in the
The number of laps pattern forms a proportion.
completed by Tom is
nonpropotional to the Time (seconds) 1 2 3 4
time.
Time (min) Distance (inches) 4 8 12 16
1 2 3 4 5 Write the rate of time to distance for each second
Number of Tom 3 6 9 12 15 in simplest form.
Laps 1 2 1 3 1 4 1
Completed Jane 4 6 8 10 12 = = =
4 8 4 12 4 16 4

Jane’s rate : 4 = 6 = 8 = 10 = 12 Answer YES
1 2 3 4 5

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