The number of people who have entered a museum on a certain day is modeled by a function (t), where t is measured in hours since the museum opened that day. The number of people who have left the museum since it opened that same day is modeled by a function g(t). If f' (t) = 380 (1.02^t) and g' (t) = 240 +240 sin (pi(t-4)/ 12), at what time t, for 1 less than or equal to t less than or equal to 11, is the number of people in the museum at a maximum?
A) 1
B) 7.888
C) 9.446
D) 10.974
E) 11
(extra info, Calc AB, Candidates Test unit)
