INPUT AS RELATED TO OUTPUT 31 
These tables serve to suggest the way least-cost combinations can 
be determined and presented. Each individual product will have 
its own special problems of calculation and presentation, but the 
general mode of attack will be the same. This can be stated briefly 
as follows: Assume various probable or possible combinations of 
factors, and determine the least-cost combination under each. In 
presenting the results, state definitely upon what assumptions each 
computation of costs under various combinations is based and pre- 
sent sufficient data to make it possible to calculate the least-cost 
combinations under other assumptions. 
The foregoing presentation is for a single crop or product. Most 
farms present a combination of products. Hence several least- 
cost combinations must be calculated for most farms. The prin- 
cipal difficulty which this presents is that the cost rates for man 
labor and horse labor vary with the different enterprises, accord- 
ing to whether they conflict or supplement each other, and accord- 
ing to the time of the year. Merely changing the proportions of 
enterprises may affect the cost rates. Cost rates for land are 
similarly affected. Least-cost determinations made on the basis of 
flat rates for labor and land will frequently be seriously misleading. 
THE MOST PROFITABLE COMBINATION OF INPUTS 
As already suggested, the least-cost combination is not neces- 
sarily the combination which will yield the largest profit. Total 
profit is the product of the profit per unit of output multiplied by 
the number of units produced; the number of units produced at a 
higher-cost combination may be enough larger than at the least-cost 
combination to more than offset the lower profit per unit. 
FOR VARIATIONS IN OUTPUT PER PRODUCTIVE UNIT 
The variation in output per productive unit may be readily illus- 
trated for the case of a man producing market milk. By buying con- 
centrate feeds he can materially change the production per cow with- 
out making any changes in the farm organization. Let us assume 
that as he increases his production the cost per pound changes, as 
shown below : 
Annual production per cow 
(pounds) Cost per 100 pounds 
6, 000 $2. 20 
7, 000 2. 00 
8, 000 1. 95 
9, 000 1. 92 
10, 000 1. 94 
11, 000 1. 98 
12, 000 2. 05 
Then the least-cost combination will be the one resulting in a pro- 
duction of 9,000 pounds per cow. The production which will give 
the greatest profit per cow will depend upon the price of milk. 
