Final answer:
The estimated direct labor-hours at the beginning of the year used in the predetermined overhead rate must have been 35,300 direct labor-hours.
Step-by-step explanation:
The estimated direct labor-hours at the beginning of the year used in the predetermined overhead rate can be calculated using the formula: Estimated manufacturing overhead / Predetermined overhead rate. In this case, the estimated manufacturing overhead at the beginning of the year is $670,700 and the actual manufacturing overhead is $665,700. The amount of overapplied overhead is $22,100. Therefore, the estimated direct labor-hours at the beginning of the year can be calculated as follows:
Estimated direct labor-hours = Estimated manufacturing overhead / Predetermined overhead rate
= $670,700 / ($665,700 + $22,100) * 36,200 hours
= $670,700 / $687,800 * 36,200 hours
= 35,300 direct labor-hours