1. The following data give real GDP, Y, capital, K, and labor, N, for the U.S. economy in various years. Year Y K N 1960 2829 3212 66 1970 4266 4802 79 1980 5834 6919 99 1990 8027 9246 119 2000 11,216 12,327 137 2010 13,063 14,769 139 Units and sources are the same as in Table 3.1. Assume that the production function is Y = AK0.3N0.7.

a. By what percentage did U.S. total factor productivity grow between 1960 and 1970? Between 1970 and 1980? Between 1980 and 1990? Between 1990 and 2000? Between 2000 and 2010?

b. What happened to the marginal product of labor between 1960 and 2010? Calculate the marginal product numerically as the extra output gained by adding 1 million workers in each of the two years. (The data for employment, N, are measured in millions of workers, so an increase of 1 million workers is an increase of 1.0.)