Answer:
The approximate amount of paint required for the job is
.
Explanation:
Given a function y = f(x) we call dy and dx differentials and the relationship between them is given by,
dy = f′(x)dx
Let s be the edge of the cube.
The volume of a cube is given by

The amount of paint needed is

Differentiating, we get:

When
and the thickness is
, this becomes

The approximate amount of paint required for the job is
.