Deluxe textbooks are made with the finest-quality paper, six-color printing, and many photographs. Moderate texts are made with three colors and a few photographs spread throughout each chapter. Economy books are printed in black and white and include pictures only in chapter openings. a. Sheridan currently allocates all overhead costs based on machine hours. The company produced the following number of books during the prior year. Determine the overhead cost per book for each book type. b. Determine the overhead cost per book, assuming that the volume-based allocation system described in Requirement a is replaced with an activity-based costing system. Round your figures to two decimal points. c. Explain why the per-unit overhead costs determined in Requirements a and b differ