LESSON 2.02:Scatterplots, Review of Independent and Dependent Variables and Using a Table of Values

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HOUSEKEEPING:1. Welcome back!2. Data Analysis Assignments3. Looking ahead!

The value of the dependent variable, as its name implies, is determined by the value of the independent variable.

ARE THESE VARIABLES RELATED?

Identify which depends on which?

Age and fitness levelsAmount of sleep the night before a test and mark on the testCalories eaten per day and weightHeight of grade 9 girls (cm) and the height of their mothers (cm)Money raised and number of cars washed

TABLE OF VALUESRelationships between 2 variables can be represented by an equation, a table of values, and a graph.

Example: Complete a table of values for y = -3x+10x y1

2

3  4  5  

Solution:To calculate each corresponding y value, substitute the given value of x.For x=1 y = -3(1)+10 y = -3+10 y = 7 Therefore, the first point is (1, 7)For x=2 y= -3(2)+10 y = -6+10 y = 4 Therefore, the next point is (2, 4)Continue for x=3, 4, and 5

Independent Dependent

EXAMPLE:

Jody works at a factory that produces square tiles for bathrooms and kitchens. She helps determine shipping costs by calculating the

perimeter of each tile. The perimeter is determined by adding the lengths of the 4

sides of each tile.

a) Calculate the perimeter and record your observations in a table of values.

b) Describe what happens to the perimeter of each tile when the side length increases by one centimetre.c) Construct a graph of the perimeter of a tile vs. the side length of the tile.

Length of side (cm)

Perimeter (cm)

1  

2  

3  

4  

5  

Length of side (cm)

Perimeter (cm)

1  

2  

3  

4  

5  

REMEMBER TAILS!

T – Title

A – Axis

I – Interval

L – Labels

S – Scale

d) Which variable is the independent variable (side length or perimeter)?e) Which variable is the dependent variable(side length or perimeter)?f) Use the graph to describe the relationship between the perimeter and side length of a tile.g) Describe the shape of the graph.

Jody’s is paid $8/hour to calculate perimeters. Calculate

her pay and record your observations in a table of values.

EXAMPLE:

Hours of work Pay ($)

1  

2  

3  

4  

5  

Hours of work

Pay ($)

1  

2  

3  

4  

5  

REMEMBER TAILS!

a) Describe what happens to her pay when the number of hours she works increases by one hour.b) Construct a graph of her pay vs. the number of hours she works.c) Which variable is the independent variable?d) Which variable is the dependent variable?e) Use the graph to describe the relationship between her pay and the number of hours she works.f) Describe the shape of the graph.

EXAMPLE:

SUCCESS CRITERIA FOR TODAY’S LESSON