Assume that individuals start to work right after school (either high school or college) and retire at age 65. Compute the present value of lifetime earnings at age 18 for a high school graduate who works immediately after graduating high school at age 18 and one who attends college for four years after graduating high school if the annual earnings of the former is $40,000 (assumed constant over time) and that of the college graduate is S50,000 (assumed constant over time) at (i) at three, five, and seven percent rate of interest, with no direct costs of college (hint: use the formula for a sum of a finite geometric series) (ii) at three, five, and seven percent rate of interest, with college costing $10,000 per year iii) Comment on the results (iv) Optional: Suppose the earnings of high school graduates grow by 2 percent per year and those of college graduates by 3 percent per year. Compute the present value of lifetime earnings at age 18 for a high school graduate and for a college graduate if the annual earnings of the former start at S40,000 and that of the college graduate starts at S50,000 at three percent rate of interest, with no direct costs of college. Comment on the results