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Costs

1.[3p]

A firm has C(q)=500+5q+0.05q2. At what output is average total cost at its minimum?

CorrectNot quite: 100

2.[2p]

For the same firm, what is marginal cost at q=150?

CorrectNot quite: 20

3.[3p]

Why does marginal cost cut average total cost at the minimum of average total cost?

Correct
The answer is: An average falls while the marginal is below it and rises while it is above, so it is stationary where they are equal
The answer is: An average falls while the marginal is below it and rises while it is above, so it is stationary where they are equal
The answer is: An average falls while the marginal is below it and rises while it is above, so it is stationary where they are equal

4.[3p]

A shop has revenue of £180,000, pays £90,000 for stock and £30,000 for staff. The owner could earn £45,000 elsewhere and the owned premises would rent for £20,000. What is its economic profit?

Correct
The answer is: Minus £5,000
The answer is: Minus £5,000
The answer is: Minus £5,000

5.[1p]

A cost that is fixed in the short run is necessarily sunk.

The answer is: False
Correct

6.[2p]

A firm's only variable input is labour at £600 a week per worker, and the marginal product of the tenth worker is 300 units. What is marginal cost, in pounds per unit?

CorrectNot quite: 2

7.[3p]

Which statements about the cost curves are correct?

Select all that apply

Correct
Correct
Correct
The answer is: It is the lower envelope of the short-run average cost curves, It never lies above short-run average cost at the same output, Marginal cost contains no fixed component, since fixed cost differentiates to zero

8.[2p]

What did Wright's 1936 study of airframe production establish?

Correct
The answer is: Cost per unit fell about 20 per cent with each doubling of cumulative output
The answer is: Cost per unit fell about 20 per cent with each doubling of cumulative output
The answer is: Cost per unit fell about 20 per cent with each doubling of cumulative output

9.[3p]

A firm chooses between plants costing C1=500+0.05q2 and C2=2000+0.0125q2. At what output are the two equally expensive?

CorrectNot quite: 200