Dependent v. Independent Variables What’s the difference?
Warmup
Objective Differentiate between independent and dependent variables Find the rate of change between two variables
Variables and Constants? What is the difference between a variable and a constant Variable Constant
Independent Variables What is controlled Represented by x Cause Time is generally independent
Dependent Variables Determined by the independent variable Outcome Effect Represented by y
Examples: Which is independent or dependent Cost and Minutes on Cell Phone Hours studied and Grade on Exam Income and education Grade on exam and hours played video games Salary and years worked Age and height Salary and hours worked Other Examples
Rate of Change Rate of Change measures the change in the dependent variable over the change in the independent variable It is synonymous with slope
Examples of where ROC is used Real Estate Finances Sports
Recall the slope formula
To Find Rate of Change Identify the independent variable, x Identify the dependent variable, y Write two sets of ordered pairs Find the slope Determine the meaning of the slope
Example The speed of sound travels 6 miles in 30 seconds and 10 miles in 50 seconds. Find the average rate of change. What is the independent variable? Time (seconds) What is the dependent variable? Distance (miles) Write as a set of ordered pairs? (30, 6) and (50, 10) Find the slope? Interpret the slope: Speed of light travels 1 mile every 5 seconds
Example Jeremy had 5 gallons of gas in his motorcycle. After driving 100 miles he had 3 gallons left. What is the independent variable? Gallons of gas What is the dependent variable? Distance (miles) Write as a set of ordered pairs? (5, 0) and (3, 100) Find the slope? Interpret the slope: Every 50 miles traveled the tank drops one gallon
Example A house valued at $225,000 pays $2020.50 in real estate taxes. A house valued at $750,000 pays $6,750 in taxes. What is the independent variable? Value of the home What is the dependent variable? Real estate taxes Write as a set of ordered pairs? (225,000, 2020.50) and (750,000, 6,750) Find the slope? Interpret the slope: You pay $9 for every $1000 your home is worth
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