How to solve these questions??

1 The following production and average cost data for two levels of monthly production volume have been supplied by a company that produces a single product:

Production volume. 1,000 units. 3,000 units

Direct materials. $13.20 per unit. $13.20 per unit

Direct labour $14.50 per unit $14.50 per unit

Manufacturing overhead. $65.40 per unit. $29.40 per unit

The best estimate of the total monthly fixed manufacturing cost is:

2 Bedok Limited absorbs manufacturing overhead using machine hour. Budgeted machine manufacturing overhead and machine hours for the current period were anticipated to be $4,800,000 and 120,000 respectively.

However, the actual machine hours being worked was only 90,000, and manufacturing overhead incurred for the year was $4,180,000. On the basis of this information, the company's year-end overhead was ____________.

A. Over-absorbed by $580,000

B. Under-absorbed by $580,000

C. Over-absorbed by $620,000

D. Under-absorbed by $620,000