An increase in saving and investment raises the capital stock and thus raises the full-employment national income and product. A model relies on simplifying assumptions.These assumptions drive the conclusions of the model. Write consumption per worker as a function of the capital stock in steady-state. The Solow Growth Model is an exogenous model of economic growth that analyzes changes in the level of output in an economy over time. The change in the capital stock is nothing but the net investment. If nothing else in the model changes, there will be a defined level of capital that the economy converges towards, no matter where the capital stock starts. Ans. The change in capital stock in the solow model is given by: a. Δ k = σ f ( k ) − δ k.