A factory monitors production rate y(t)=100+5t units/hr over [2, 9] using irregular measurement times t_0=2<…

A∑_{i=1}ⁿ y(t_{i−1})·Δt_i

B∑_{i=1}ⁿ y(t_i)·Δt_i

C∑_{i=1}ⁿ y(t_{i−1} + ½Δt_i)·Δt_i

D∑_{i=1}ⁿ y(t_{i−1} + 0.6Δt_i)·Δt_i