Final answer:
a) -$3.73 per direct labor hour.
The predetermined overhead rate is calculated by dividing the total estimated manufacturing overhead cost by the estimated total allocation base, giving us $3.73 per direct labor hour.
Step-by-step explanation:
To calculate the predetermined overhead rate, we must divide the total estimated manufacturing overhead cost by the estimated total allocation base of direct labor hours. The total overhead cost is given as $28,000, comprising $13,000 fixed and $15,000 variable costs. The total allocation base is given as 7,500 direct labor hours.
Using the formula:
Predetermined Overhead Rate = Total Estimated Overhead / Total Estimated Allocation Base
We get:
Predetermined Overhead Rate = $28,000 / 7,500 hours = $3.73 per direct labor hour. Therefore, the correct answer is a) -$3.73 per direct labor hour.