Crude oil imports to one country from another for 2009–2013 could be approximated by the following model where t is time in years since the start of 2000.
I(t) = −31t² + 800t − 1,000 thousand barrels per day (9 ≤ t ≤ 13)
According to the model, approximately when were oil imports to the country greatest? HINT [See Example 1.] (Round your answer to two decimal places.)
t =
