A perfect competitor charges a price of $5. The fi rst worker he would hire would have a marginal physical product of 20, the second worker he would hire would have a marginal physical product of 18, the third worker would have a marginal physical product of 16, and the fourth worker would have a marginal physical product of 14. (a) How many workers would he hire if the wage rate were $90? How much would his wage bill be? (b) How many workers would he hire if the wage rate were $70? How much would his wage bill come to?