30.31.2–3 P.M. 70 100
3–4 P.M. 120 220
The table shows one approach, based on the Midpoint Rule.
We estimate that there had been about 100 visitors by 3 P.M. and 220 by 4
P.M., so the 200th visitor arrived between 3 and 4 P.M.(B) unit (to
the right).(C) We partition [0, 2] into n equal subintervals each of time Δt hr. Since
the 18-wheeler gets (4 + 0.01v) mi/gal of diesel, it uses . Since it
covers v · Δt mi during Δt gal in t hr, it uses · v · Δt hr. Since v =
80 , we see that the diesel fuel used in the first 2 hr is