The following data give real GDP, Y, capital, K, and labor, N, for the U.S. economy in various years. Year  ...

  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   2502   2695   65.8 
1970   3772   4044   78.7 
1980   5162   5831   99.3 
1990   7113   7809   118.8 
2000   9817   10,392   136.9 
2007   11,524   11,849   146.0 
Y is real GOP in billions dollars; K is real net stock of fixed private nonresidential capital in billions of
dollars; N is civilian employment in millions of workers 
That the production function is:
7 . 0 3 . 0
N AK Y 
 .
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 2007?
b.  What happened to the marginal product of labor between 1 960 and 2007? Calculate the
marginal product numerically as the extra output gained by adding 1 million workers in each of
the two years.