One of Spa Magic's products is a whirlpool spa. Two processing departments are Involved In the whirlpool spa's manufacture. The tub Is assembled In one department, and a second department assembles and Installs the motor. There was no beginning or ending work In process In either department on March 1. During March, the company Incurred the following costs In the manufacture of 5,000 whirlpool spas. Motor Tub Department Department Direct materials $1, 250, 090 $750, 090 Direct labor 100, 900 60, 060 Manufacturing overhead 600, 090 30, 090 Required: a-1. Compute the cost per-unit of a tub assembly transferred to the Motor Department for the month of March. a-2. Compute the cost per-unit of assembling a motor and installing it for the month of March. a-3. Compute the cost per-unit of a completed whirlpool spa sent to the finished goods warehouse for the month of March. a-4. Compute the cost per-unit of direct materials used In assembling a tub for the month of March. a-5. Compute the cost per-unit of direct labor cost of assembling and installing a motor for the month of March. b. Which of these unit costs would be most useful to management in evaluating the overall monthly efficiency of the Motor Department