The economy has grown by 4% per year over the past 30 years. during the same period the labor force has grown by 1% per year and the quantity of physical capital has grown by 5% per year. each 1% increase in physical capital per worker is estimated to increase productivity by 0.4%. assume that human capital has not changed during the past 30 years. what is the growth rate of productivity? a. how fast has physical capital per worker grown? b. how much has growing physical capital per worker contributed to productivity growth? c. how much has growing physical capital per worker contributed as a percentage of total productivity growth? d. how much has technological progress contributed to productivity growth? e. how much has technological progress contributed as a percentage of productivity growth?