When we are given data and use Excel to create the exponential model, we may need to be able to identify the growth or decay rate, r. Once we have written the model in Q form we are almost there! Example: Suppose you enter data in Excel, and Excel gives you the exponential model "y" equals 3.3 8 "e" Superscript, 0.1 2 0 4 "x" , Baseline 1) Convert to Q form, as on the previous slide: "Q" equals 3.3 8 ( 1.1 2 7 9 ) Superscript, "t" , Baseline 2) Since the value inside the parentheses is the same thing as 1+r, we can set it equal to 1+r: 1 plus "r" equals 1.1 2 7 9 3) Subtract 1 from both sides to solve for r: "r" equals 0.1 2 7 9 or 12.79% If we wanted to, at this point we could write our model as "Q" equals 3.3 8 ( 1 plus 0.1 2 7 9 ) Superscript, "t" , Baseline You try it! Refer back to the equation that you converted to Q form on the previous slide, "y" equals 2.2 8 3 "e" Superscript, 0.1 5 9 2 "x" , Baseline . What