Final Answer:
1. The final equation is incorrect because the profit function,
, is calculated as
but the correct form should be

Step-by-step explanation:
The correct profit function,
is determined by subtracting the cost function,
from the product of the selling price function,
, and the quantity sold function,
The correct expression is
Substituting the given functions, we get

The incorrect calculation likely stems from a misunderstanding of the order of operations. In the employee's calculation, it appears that
and
are multiplied first, and then
is subtracted. However, the correct order is to multiply
and
first, and then subtract
The correct equation accounts for the cost of production before subtracting it from the revenue.
In summary, the final equation is incorrect due to an error in the order of operations. The correct form of the profit function is
, ensuring an accurate representation of the profit derived from selling stress balls at different prices.