2 -- In a model with no government and no foreign sector , if commmption is 200 , investment is 300-100 , and the level of squilibrium income Y Y = 1,200 , then the marginal is propensity to save is : 1-0.10 2 0.20 3 -0.25 4-0.5 3- Assume a model of the expenditure sector with no government involvement . The autonomous comumption is a 300 , investment is 1980 , nd net export is . If the model is in equilibrium at Y - 2000 , we can conclude that the marginal propensity to consume must be : a - 0.9 b - 0.8 c - 0.5 d - 0.2 4 - To ensure this is accepted , the US government tacitly promises the public that it will not print money : 1 . Commodity money 2. Paper money 3 . barter cash 4. exchange rates