Office rents after the economy softened the sky-high office

Question

Question: OFFICE RENTS After the economy softened, the sky-high office space rents of the late 1990s started to come down to earth. The function R gives the approximate price per square foot in dollars, R(t), of prime space in Boston's Back Bay and Financial District from 1997 (t = 0) through 2002, where

R(t) = -0.711t³ + 3.76t² + 0.2t + 36.5              (0 ≤ t ≤ 5)

Show that the office space rents peaked at about the middle of 2000. What was the highest office space rent during the period in question?