0.85
1) Since the exponential model of decay points out, in this case, a devaluation. then, we can write the following for a 15% decay:
[tex]\begin{gathered} y=a(1-0.15)^{\frac{t}{12}} \\ y=a(0.85)^{\frac{t}{12}} \end{gathered}[/tex]Note that 1, refers to 100%. And a to the initial value.
2) So the base is 0.85 and a is the initial value. This function will provide us the devaluating value over time.
