# Five years ago, you purchased a riding lawn mower for $1600. Recently, you resold the mower for$525. Assume that the value of the mower decays exponentially with time. How do you write an exponential decay model?

Apr 12, 2017

Let me start with exponential decay. $r = - 0.2229$

#### Explanation:

$V = V o \cdot {e}^{- r \cdot t}$
$\ln \left(\frac{525}{1600}\right) = - r \cdot 5$
$r = - 0.2229$ (approximately).