Exercise 7 Page 168

In the example we were shown how to write an equation for power generation for all power sources other than hydropower. Now we have been given the data for hydropower specifically and are asked to construct a new model. We will follow the same pattern as in the example. Megawatt hours (millions)= Initial value+Rate of change * Years since2007 In this equation, the independent variable x is the number of years since 2007 and the dependent variable y is the output in megawatt hours. y= Initial value+Rate of change * x The initial value is the number of million megawatt hours used in 2007. The exercise tells us that it was 248. Let's write that into the equation. y= Initial value+Rate of change * x ⇓ y= 248+Rate of change * x The rate of change we can find by using the given points, ( 0, 248) and ( 5, 277), and the Slope Formula. We can now write our linear model for electricity generated by hydropower in the U.S. y=248+5.8x