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).

Question

1940 1950 1960 1970 1980 1990
t 0 10 20 30 40 50
E 6.7 9.6 13.1 18.1 20.4 19.5

Estimate the integral: ∫^{50}_0 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)

Answer 1

∆t = 10, so
∫[0..50] f(t) dt ≈ ∑[k=1..5] f(t_k) ∆t

R_5 = 10(9.6+13.1+18.1+20.4+19.5)