Zolta Co, a manufacturing firm, uses a standard costing system. It makes a single product, ZIN, using a single raw material XUE. Standard costs relating to ZIN have been calculated as follows. Standard cost schedule ZIN Per unit (RM) Direct material, XUE, 15 kg at RM25 per kg 375 Direct labour, 6 hours at RM8 per hour 48 Variable overhead, 6 hours at RM6 per hour 36 Total standard costs 459 The standard selling price of a ZIN is RM600 and Zolta Co produces 5,000 units a month. During April 2020, 4,500 units of ZIN were produced. Relevant details of this production are as follows: Direct material XUE - 65,000 kgs costing RM1,592,500 were bought and used. Direct labour 25,000 hours were worked during the month and total wages were RM205,000. Variable production overhead The actual cost of the month was RM155,000. Inventories of the direct material XUE are valued at the standard price of RM25 per kg. Each ZIN was sold for RM650. c) Variable production overhead variances, analysed into expenditure and efficiency variances. (6 marks)