Suppose a demand-driven economy in which people consume in the current period some fraction of

their income in the previous period (described by the following equations):

Yt = Ct + It + Gt

Ct = cYt−1, 0 < c < 1

It = I0

Gt = G0

问:Suppose I0=200, G0=600 and Y0=3000 (initial conditions). What will the new

long-run equilibrium GNP value be? How many periods are required for 80% of

GNP change (from initial condition to equilibrium) to be realized?