Question: The operating rate (expressed as a percent) of factories, mines, and utilities in a certain region of the country on the tth day of 2008 is given by the function
f(t) = 80 + 1200t/(t2 + 40,000) (0 ≤ t ≤ 250)
On which of the first 250 days of 2008 was the manufacturing capacity operating rate highest?