Define independent variable.
Independent variable (x) is a factor that cannot be controlled. Nothing else can change this variable. Time is almost always independent.
How do you know if a word problem gives you a constant without having to do a calculation?
The word "per"
y=mx
y = dependent
m = constant of proportionality
x = independent variable
What is the independent and dependent variable for the following table?
independent = # of tickets
dependent = Cost ($)
What is the independent and dependent variable for this graph?
independent = time (min)
dependent = distance (ft)
Define dependent variable.
Dependent variable (y) is a factor that can change based on the independent variable. It relies on the other variable. Money is almost always dependent.
y=35x
Tony drives his car 100 miles using 4 gallons of gas. Write an equation for the proportional relationship.
What is the constant of proportionality and what does it mean?
constant = 13
13 apples per tree
What ordered pair can you use to find the constant of proportionality?
(5,6)
(10,12)
(15,18)
What is another word for 1 and when do we use it?
1 = "per". We use it when we have a unit rate/constant of proportionality
Imagine NEMS has a car wash to raise money. Assume this is proportional. After washing 15 cars, $120 is raised. What is the constant and what does it represent?
constant = 8
Means $8 per car
Ruby goes to workout at the local gym. To pay the membership, Ruby follows the equation y = 25x where he has to pay the total cost for a certain amount of months at a time. What is the constant and what does it represent?
Constant = 25
$25 per month
What does the constant of proportionality mean in this table?
$75 per ticket
What is the constant of proportionality?
1.5
Define constant of proportionality. How do we find unit rates? Give the formula and what each part represents.
the ratio of dependent quantities to independent quantities having an equivalent, constant rate
y/x = dependent / independent
Amber earns $490 for working 40 hours for her summer job each week. What is the constant of proportionality? And what is the equation?
constant = $12.25 per hour
y=12.25x
Sandy sells ice cream using the equation y=0.9x to represent the total cost and number of scoops of ice cream. What is the constant and what does it mean?
$0.90 per scoop
What does ? have to be to make the table proportional?
42
What does the constant of proportionality mean in this graph?
$1.50 per magnet
How do you know when a relationship between two variables is proportional? There are three factors.
1) constant unit rate (y/x)
2) goes through origin (0,0)
3) y=mx
y = 45.2x
Write your own proportional relationship equation and identify each part (what x is, what y is, and what the constant represents).
y =
m =
x =
A
What is the equation to this proportional relationship?
y =1.2x