Wolf Manufacturing expects the following overhead costs in the current year: 

Indirect material..............................................$ 45,000 

Indirect labor......................................................55,000 

Depreciation of machinery.............................160,000 

Repair and maintenance on machinery........135,000 

Utilities and taxes...............................................55,000 

Total.................................................................$450,000 

It expects to use 25,000 direct labor hours at a cost of $525,000 and 15,000 machine hours during the year. 

Required 

Justify the selection of an appropriate allocation base and calculate the predetermined overhead allocation rate.