On April 22, 2020, Sandhill Enterprises purchased equipment for $138,700. The company expects to use the equipment for 11,500 working hours during its 4-year life and that it will have a residual value of $14,500. Sandhill has a December 31 year end and pro-rates depreciation to the nearest month. The actual machine usage was: 1,500 hours in 2020; 3,000 hours in 2021; 3,600 hours in 2022; 2,600 hours in 2023; and 1,000 hours in 2024.

a) Calculate units of production