Use the following information of Alfred Industries. Standard manufacturing overhead based on normal monthly volume: Fixed ($304,200 20,000 units) Variable ($100,000 20,000 units) $ 15.21 5.00 $ 20.21 Units actually produced in current month Actual overhead costs incurred 18,000 units (including $300,900 fixed) $383,800 Compute the overhead spending variance and the volume variance. (Indicate the effect of each variance by selecting "Favorable" or "Unfavorable". Select "None" and enter "O" for no effect (i.e., zero variance).) Overhead spending variance Overhead volume variance