Problem 1. (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 7.3 9.1 13.3 18.3 20.5 19.8 (a) Using left endpoints, estimate the integral: 1 0 s(t ) at = (b) Using right endpoints, estimate the integral: -50 ( f ( t ) at ~ 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