# Relationship between returns to scale and cost curves microeconomics

### Long-Run Average Cost LRAC and Marginal Cost Curves LMC

Calculating total cost: This graphs shows the relationship between fixed cost and variable Cost curve: This graph is a cost curve that shows the average total cost, In economics, returns to scale describes what happens when the scale of . The Marginal Cost (MC) of a sandwich will be the cost of the worker divided by the number Difference between diminishing returns and dis-economies of scale. The nature of the returns to scale affects the shape of a business's average cost curve – when there are sizeable increasing returns to scale, and then we expect .

This shape of the marginal cost curve is directly attributable to increasing, then decreasing marginal returns and the law of diminishing marginal returns.

## Cost curve

Thus marginal cost initially falls, reaches a minimum value and then increases. When the marginal cost curve is above an average cost curve the average curve is rising.

When the marginal costs curve is below an average curve the average curve is falling. This relation holds regardless of whether the marginal curve is rising or falling. Stated otherwise, LRMC is the minimum increase in total cost associated with an increase of one unit of output when all inputs are variable.

## The Law of Diminishing Marginal Returns

The long-run marginal cost curve tends to be flatter than its short-run counterpart due to increased input flexibility as to cost minimization. The long-run marginal cost curve intersects the long-run average cost curve at the minimum point of the latter. Long-run marginal cost equals short run marginal-cost at the least-long-run-average-cost level of production. Graphing cost curves together[ edit ] Cost curves in perfect competition compared to marginal revenue Cost curves can be combined to provide information about firms.

In this diagram for example, firms are assumed to be in a perfectly competitive market.

### Production and costs | AP®︎ Microeconomics | Khan Academy

In a perfectly competitive market the price that firms are faced with would be the price at which the marginal cost curve cuts the average cost curve. Cost curves and production functions[ edit ] Assuming that factor prices are constant, the production function determines all cost functions.

In this case, with perfect competition in the output market the long-run market equilibrium will involve all firms operating at the minimum point of their long-run average cost curves i.

If, however, the firm is not a perfect competitor in the input markets, then the above conclusions are modified. For example, if there are increasing returns to scale in some range of output levels, but the firm is so big in one or more input markets that increasing its purchases of an input drives up the input's per-unit cost, then the firm could have diseconomies of scale in that range of output levels.

### Cost curve - Wikipedia

Conversely, if the firm is able to get bulk discounts of an input, then it could have economies of scale in some range of output levels even if it has decreasing returns in production in that output range.

If MC equals average total cost, then average total cost is at its minimum value. If MC equals average variable cost, then average variable cost is at its minimum value. What factors would cause this? As more workers are added, they are able to divide the respective tasks and specialize. When the marginal product is increasing, the total product increases at an increasing rate. If a business is going to produce, they would not want to produce when marginal product is increasing, since by adding an additional worker the cost per unit of output would be declining.

In The Wealth of Nations, Adam Smith wrote about the advantages of the division of labor using the example of a pin maker. He pointed out that an individual not educated to the business could scarce make one pin a day and certainly not more than twenty.

But the business of pin making is divided up into a number of peculiar trades and each worker specializes in that trade.

As more workers are added, the capital, i. The law of diminishing marginal returns states that as successive amounts of the variable input, i. As the marginal product begins to fall but remains positive, total product continues to increase but at a decreasing rate. As long as the marginal product of a worker is greater than the average product, computed by taking the total product divided by the number of workers, the average product will rise.

For students, it is often easiest to remember when you think about your grade point average.

But if your g. Thus the marginal product will always intersect the average product at the maximum average product. There may even come a point where adding an additional worker makes things so crowded that total product begins to fall.

In this case the marginal product is negative. In our example, adding the ninth and tenth worker yields lower output than what was produced with only eight workers. So how many workers should be employed? We know that we would not stop in the region where marginal product is increasing and we would not produce in the region where marginal product is negative.

Thus we will produce where marginal product is decreasing but positive, but without looking at the costs and the price that the output sells for, we are unable to determine how many workers to employ. A production function shows the output or total product as more of the variable input, in our case labor is added. The function shows the regions of increasing marginal product, decreasing marginal product, and negative marginal product.

Practice Residential construction crews are often three to eight people depending on the type of work. Think of what factors would cause increasing and decreasing marginal productivity in construction. Think of another industry and what would be the ideal number of workers? Key Equations Section Short Run Costs Accounting vs.