Answer:
The average revenue is decreasing at a rate of 0.0021 dollars per belt when 545 belts have been produced and sold.
Step-by-step explanation:
We are given the following in the question:
[tex]R(x) = 40x^{\frac{4}{7}}[/tex]
where R(x) is the revenue function and x is the number of belts.
Average revenue:
[tex]\bar{R}(x) = \dfrac{R(x)}{x} = \dfrac{40x^{\frac{4}{7}}}{x} = 40x^{\frac{-3}{7}}[/tex]
Rate of change of average revenue:
[tex]\dfrac{d\bar{R}(x)}{dx} = \dfrac{d}{dx}(40x^{\frac{-3}{7}}) = \dfrac{-120}{7}x^{\frac{-10}{7}}[/tex]
Putting x = 545
[tex]\dfrac{d\bar{R}(545)}{dx} = \frac{-120}{7}(545)^{\frac{-10}{7}} = -0.0021[/tex]
Thus, when 545 belts have been produced and sold, the average revenue is decreasing at a rate of 0.0021 dollars per belt.