(1 point) The following table gives the the approximate amount of emissions, E, of nitrogen oxides in millions of metric tons per year in the US. Let t be the number of years since 1940 and E = f(t). t 1940 1950 1960 1970 1980 1990 E 7.1 9.5 12.9 18.4 20.6 19.4 (a) Using left endpoints, estimate the integral: f (t) dt ~ (b) Using right endpoints, estimate the integral: 50 f(t) dt ~ Be sure that you know what the units of your answer are, and what its meaning is! (Original data from the Statistical Abstract of the US, 1992) Note: You can earn partial credit on this problem.Find the value of , f(x ) dac, given than f(x) is even, S_ f(x) da = 5, and , f(x) dac = 9. Si f(x) dac =