Answer:
Private saving (Sprivate) is equal to disposable income minus consumption:
Sprivate = Y - T - C = 15,000 - 3,000 - 9,000 = 3,000
Public saving (Spublic) is equal to government revenue minus government spending:
Spublic = T - G = 3,000 - 3,600 = -600
National saving (S) is equal to the sum of private and public saving:
S = Sprivate + Spublic = 3,000 - 600 = 2,400
Investment (I) is given by the investment function:
I = 3,900 - 100r
Equating investment to national saving gives:
I = S
3,900 - 100r = 2,400
Solving for r:
r = 15%
Therefore, the equilibrium real interest rate is 15%.
Substituting r = 15% into the investment function gives:
I = 2,400
Therefore, investment is 2,400.
Finally, to determine if the government has a budget surplus or deficit, we need to calculate the government's budget balance, which is equal to government revenue minus government spending:
Budget balance = T - G = 3,000 - 3,600 = -600
Since the budget balance is negative, the government of Flatland has a budget deficit.