Consider a Solow model with no population growth (i.e., n = 0). The production function has constant returns to scale and technology is neutral, Y = AF (K, N). The production function takes the intensive form: Y/N = AF (K/N, 1) A f (K/N), where K/N is capital per worker and Y/N is output per worker. The saving rate of the economy is s and the depreciation rate is d.

Explain graphically and intuitively

(a) Can an increase in the saving rate sustain growth forever?