A partial standard cost card for the single product produced by Mercer Company is given below: Direct materials: 3 pounds @ $8 per pound Direct labor:? hours @? per hour Last period the company produced 4,000 units of product. Cost and other data associated with this production are given below: Direct materials purchased and used, at cost $103,320 Direct labor cost incurred (10,400 hours) $120,640 Materials price variance $2,520 Unfavorable Labor efficiency variance $4,800 Unfavorable Total labor variance $640 Unfavorable The direct materials purchases variance is computed when the materials are purchased. Required: 1. Determine the standard direct labor rate per direct labor hour