Parker Plastic, Incorporated, manufactures plastic mats to use with rolling offce chairs, its standard cost information for last year follows: Parker Plastic had the following actual results for the past year: Required: Colculate Parker Plastic's variable overhend rate and efficiency variances and its over. or underapplied variable overhead. Note: Do not round intermediate calculations. Indicate the effect of each variance by selecting "F" for favorable, " U " for unfavorable, and "None" for no effect (Le., zero variance)