Answer: $2,720
Step-by-step explanation:
Total materials handling cost for specialty windows = Proportion of total units * Total materials handling cost
Proportion of total units = Specialty units / (Specialty windows + Wall mirrors)
= 6,000 / (6,000 + 9,000)
= 0.4
Total material handling cost for specialty windows = 0.4 * 6,800
= $2,720