Part A
- independent variable = number of hours
- dependent variable = total amount saved
The equation would be y = 12x+200 where x is the number of hours and y is the amount saved. The 200 is what you already have, and then you add on 12x additional dollars.
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Part B
- independent variable = number of miles you drive
- dependent variable = amount of gas in the car
equation would be y = -0.10x+12. You start off with 12 gallons and each time you use up 0.10 gallons of gas for each mile you drive, so in total you use up 0.10x gallons
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Part C
- independent variable = number of extra credit assignments turned in
- dependent variable = test grade
Equation is y = 2x+60. You add on 2x additional points to the 60 you already have
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Part D
- independent variable = number of text messages sent
- dependent variable = total monthly bill
x is the number of messages and y is the total monthly bill, so the equation would be y = 0.25x + 35
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Part E
- independent variable = number of cookies eaten per day
- dependent variable = total caloric intake per day
eating x cookies, at 120 calories a piece, means y = 120x is the total number of calories you consume per day. This is just considering the cookies of course and not other meals.
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In each case, the independent variable is the variable that is allowed to change and you know this value (or are given it). For instance, you know how many miles you drive and it varies. The dependent variable relies on the value chosen for the independent variable. So as x changes, then so does y.
