Please help me understand the following exercise, with some explanations thank you :

6. The minimum efficient of scale for a firm occurs

Select one:

a.at the point where average cost begins to decline

b.when the average fixed cost curve begins to rise

c.when marginal cost is its minimum

d.none of the above

8. Decreasing returns to scale can result from...

Efficiency in the production process.

Efficient management of inputs.

Perfect substitutability of inputs.

All inputs are increased except one which has been forgotten.

Efficient coordination in management.

9. A certain firm produces and sells staplers. Last year, it produced 7,000 staplers and sold each stapler for $6. In producing the 7,000 staplers, it incurred variable costs of $28,000 and a total cost of $45,000.

The firm's accounting profit for the year was

Select one:

a.$17000

b.-$5000

c.-$3000

d.$7000

10. Adrian's Premium Chocolates produces boxes of chocolates for its mail order catalogue business. She rents a small room for $150 a week in the downtown business district that serves as her factory (K). She can hire workers (L) for $275 a week. There are no implicit cots.

#Workers #Boxes MPL Cost of K Cost of L Total Cost

0 0 ? ? ? ?

1 ? 330 150 275 425

2 630 ? ? ? ?

3 ? 150 ? 825 975

4 890 ? ? ? ?

5 950 60 ? 1375 ?

6 ? 10 ? ? 1800

What is the total cost associated with making 890 boxes of premium chocolates per week?

Select one:

a.$1400

b.$1250

c.$1325

d.$1025

17. A firm is experiencing increasing returns to scale if

Select one:

a.cost is proportional to output

b.long run average cost as the firm expand its scale of operation

c.output more than doubles when all inputs are doubled

d.none of the above

18. A certain firm produces and sells staplers. Last year, it produced 7,000 staplers and sold each stapler for $6. In producing the 7,000 staplers, it incurred variable costs of $28,000 and a total cost of $45,000.

In producing the 7,000 staplers, the firm's average variable cost was

Select one:

a.$6

b.$4

c.$2

d.$8