Based on the selling price of the 8 units and 9 units, the marginal revenue from selling the ninth unit is $405.
This can be found as:
= Revenue from selling 9th unit - Revenue from selling 8th unit
Solving gives:
= (9 x 445) - (8 x 450)
= 4,005 - 3,600
= $405
Find out more on marginal revenue at https://brainly.com/question/10822075.
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