Productivity of a Country - The productivity of a South American country is given by the function f(x,y)=30x0.15y0.85 when x units of labor and y units of capital are used. a) What are the marginal productivity of labor and the marginal productivity of capital when the amounts expended on labor and capital are 200 units and 15 units, respectively? b) Should the government encourage capital investment rather than increased expenditure on labor at this time to increase the country's productivity