Exercise 4-8B Allocating indirect cost over varying levels of prodcution

Cornerstone Company's annual factory depreciation is $630,000. Cornerstone estimated it would operate the factory a total of 3,600 hours this year. The factory operated 300 hours in November and 200 hours in December.

Why would Cornernerstone need to allocate factory depreciation cost? How much depreciation cost should Cornerstone allocate to products made in November and those made in December?