essential question: what are some facts that you can find out about a real-world situation from...
TRANSCRIPT
Essential Question: What are some facts that you can find out about a real-world situation
from reading a graph that models a situation.
You can model many real world situations with linear equations.
Remember that a graph of an equation shows the solutions of that equation
However, for discrete situations, not every point may represent a reasonable value.◦ Remember: Discrete Data is Counted◦ Continuous Data is Measured
Example 1◦ A car dealership has 40 cars in stock. The auto
manufacturer will deliver new cars to the dealership by car carrier. Each carrier holds 6 cars. Write a linear function that relates the number of carriers used to the total number of cars at the dealership. Graph the function that models the situation. The total equals 40 plus 6 times the number of
number of cars car carriers Let x = the number of car carriers
Let y = the total number of cars y = 40 + 6x
Example 1 (continued)◦ y = 40 + 6x◦ Let’s reorder the right side… y = 6x + 40
◦ Start with the y-intercept b = 40
◦ Use rise/run to makesuccessive points Up 6, over 1
◦ Discrete points (not a line) We’re counting # of car carriers
Your Turn◦ A sporting goods store sells cans of tennis balls.
There are 3 tennis balls in each can. Write a linear function that relates the number of cans to the total number of tennis balls. t = number of tennis balls
c = number of cans t = 3n
1 2 3 4 5 6 7 8 9 x
2
4
6
8
10
12
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18
20y
Example 2: Analyzing Linear Graphs◦ Students in a ninth-grade class drew the following
graph to represent how much money would be in the class fund after washing cars at a fundraiser.
◦ What does the slopeand y-intercept ofgraph mean for thegiven situation? y-intercept is $25 Slope is 3 It means the class
charged $3/car, and started with $25 in their account.
If the graph had thesame slope, but ay-intercept of 15,what would thatmean?◦ It would mean that
the class started with$15 instead of $25
If the graph had a slope of 5, what could you conclude?◦ That the class charged $5/car instead of $3.
Your Turn◦ Suppose you drew the following graph to
represent how far you ride your bike at a steady rate.
◦ What is your rate? 12 miles/hr
◦ If the graph had a slope of 10, what could you conclude about your bike ride? Your rate would be 10 miles/hr