Data concerning manufacturing overhead for Analina Industries are presented below. The Mixing Department is a cost center.

An analysis of the overhead costs reveals that all variable costs are controllable by the manager of the Mixing Department and that 50% of supervisory costs are controllable at the department level.

The flexible budget formula and the cost and activity for the months of June and July are as follow

a) Prepare the responsibility report for the Mixing Department for each month.

b) Comment on the manager's performance in controlling costs during the two-month period