Estimating the Marginal Return to Schooling Suppose Carl's wage-schooling locus is given by the following schedule: Suppose that the only cost of schooling is the opportunity cost of not working and earning money. Also assume that Carl s life is infinitely long (this is a good approximation when the time horizon is long). Derive the marginal rate of return schedule. When will Carl quit school if his discount rate is 4 percent? Why? What will Carl's optimal schooling choice be if his discount rate is 12 percent? Why? Suppose the government impose? an income tax of 20 percent. What is the effect of this income tax on Carl's educational attainment? Why