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Sanford Ltd. produces a product with the following standard costs: Variable overhead (8 hours) 21.57 Fixed overhead (8 hours) 35.00 The fixed overhead rate is based on a standard monthly volume of 16184 units. The actual results for the month of July 20x5 are as follows: Direct labour (91400 hours) Variable overhead Fixed overhead Units produced and sold 1023000 329958 580000 15307 units What is Sanford's variable overhead efficiency variance for July 20x5 (note: a negative number represents an unfavourable variance and a positive number represents a favourable variance)? Select one: a. $112114 b. 5-83521 c583735 d. 50