The cost function is
,
is the ordering and transportation cost for components used, measured in thousands of dollars.
is the order size in hundreds.
Find the rate of change of cost function.
\
Apply derivative on each side with respect to
.

Quotient rule of derivatives :
.

.
(a)
\Find the rate of change of cost function at
.

Substitute
in the above function.

thousand/
components.
(b)
\Find the rate of change of cost function at
.

Substitute
in the above function.

thousand/
components.
(c)
\Find the rate of change of cost function at
.

Substitute
in the above function.

thousand/
components.
Observe the value of
for different values of
.
As the size of the order increases, rate of change in cost decreases.
\(a)
thousand/
components.
(b)
thousand/
components.
(c)
thousand/
components.
As the size of the order increases, rate of change in cost decreases.