# Deciding on a maintenance scenario

### **Paint or replace ?**

**The first option**, a
straightforward replacement after 4 years, can be described with the following
expression:

PW = -P + {t(P-S)/n}(P/A, i%, n) and **PW = -$4,577**

**The second option**, a coating
with annual maintenance valued at 10% installation, and an installation cost
equal to P, can be described as:

PW = -P + {t(P-S)/n}(P/A, i%, n) - (1-t)(X)(P/A, i%, n), where X
= 0.1 P

PW = -P + 0.364 P - 0.185 P

**PW = -0.821 P**

Equating the first option cost to this expression yields the
maximum installation cost of the coating:

-0.821 P = -$4,577

**P = $5,574 is the answer for the installation cost of the
coating**