Select the formula below used to compute a companys predetermined overhead rate? a. Predetermined overhead rate = Actual total manufacturing overhead costs Estimated total units in the allocation base b. Predetermined overhead rate = Estimated total manufacturing overhead costs Estimated total units in the allocation base c. Predetermined overhead rate = Estimated total units in the allocation base Estimated total manufacturing overhead costs d. Predetermined overhead rate = Estimated total manufacturing overhead costs Actual total units in the allocation base.