You have answered 0 out of 2 parts correctly 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 a Using left endpoints estimate the integral 5 5 f b Using right endpoints estimate the integral 6 5 0 ft Be sure that you know what the units of your answer are and what its meaning is f t dt 690 f t dt 815 t 1940 7 4 1950 1960 1970 1980 1990 9 3 13 3 18 1 21 3 19 6