Answer:
Increase by $5,500.
Explanation:
The computation of the change in the operating income is shown below:
Data given in the question
Number of defective telephones = 600
Cost = $9,000
Scrap for each = $9
Entire batch cost = $6,500
Sale value per unit = $20
Now in the case of defective telephones, the change in operating income is
= 600 units × $20 - $6,500
= $12,000 - $6,500
= $5,500