From our data marginal product increases up to the employment of the seventh worker. Whereas the second worker raises TP by 20 units, the third worker does so by 30 units, etc. It is not that the third works harder than the second: recall that we assumed workers to be homogeneous. The reason is due to the spare capacity in the fixed factor. In essence, there are too many units of capital relative to the employment of labour and capital is under- utilised. However, as more workers are employed, capital becomes more efficiently utilised and marginal product rises. Beyond the seventy worker MP falls, as there become too many people working with the fixed capital. Capital is now over- utilized, and becomes increasingly so.