koehler makes handheld calculators in two model: basic and professional.koehler estimated $721,000 of manufacturing overhead and 515,000 machine hours for the year. the basic model actually consumed 230,000 machine hours, and the professional model consumed 285,000 machine hours. requirements are: 1. compute the predetermined overhead allocation rate using machine hours as the allocation base. 2. how much overhead is allocated to the basic model? to the professional model? select the formula, then enter the amounts to compute the predetermined overhead allocation rate.