The Abu Dhabi Bread Company bakes muffins for distribution to grocery stores in Abu Dhabi and Al Ain. The company has two indirect cost categories: variable manufacturing overhead and fixed manufacturing overhead. Variable manufacturing overhead and fixed manufacturing overhead are allocated to products on the basis of standard direct manufacturing labour-hours. The following is budget cost and usage data for the Abu Dhabi Bread Company: Direct manufacturing labour 2 minutes per muffin Variable manufacturing overhead $10 per direct manufacturing labour-hour Fixed manufacturing overhead $4.0 per direct manufacturing labour-hour The budgeted output is 2,200,000 muffins The Abu Dhabi Bread Company provides the following actual data for the year ended December 31, 2014: Actual production Direct manufacturing labour Actual variable manufacturing overhead Actual fixed manufacturing overhead 1,800,000 muffins 45,000 hours $640,000 $270,000 Required: a. Compute the spending and efficiency variance for variable manufacturing [4 Marks] [4 Marks]. [4 Marks). overhead b. Compute the spending and production volume variance for fixed manufacturing overhead c. Explain TWO possible causes of EACH of the variances you have computed in a and b above