<Tr> <Td> </Td> <Td> This article may lack focus or may be about more than one topic . Please help improve this article, possibly by splitting the article and / or by introducing a disambiguation page, or discuss this issue on the talk page . (September 2011) </Td> </Tr> <P> The defining feature of diminishing marginal returns is that as total investment increases, the total return on investment as a proportion of the total investment (the average product or return) decreases . Suppose, for example, that 1 kilogram of seed applied to a certain plot of land produces one ton of crop, that 2 kg of seed produces 1.5 tons, and that 3 kg of seed produces 1.75 tons . In formulaic terms, the i (\ displaystyle (i)) th kg of seeds produces 1 2 i − 1 (\ displaystyle (\ frac (1) (2 ^ (i - 1)))) additional tons of crop . The return from investing the first kilogram is 1 t / kg . When 2 kg of seed is invested, the return is 1.5 / 2 = 0.75 t / kg, and when 3 kg is invested, the return is 1.75 / 3 = 0.58 t / kg . </P> <P> In formulaic terms, for this example, the diminished marginal return is: </P> <P> D = 1 X ∑ i = 1 X 1 2 i − 1 (\ displaystyle (\ text (D)) = (\ frac (1) (X)) \ sum _ (i = 1) ^ (X) (\ frac (1) (2 ^ (i - 1)))) </P>

Is used to describe the additional cost of producing one more unit