A helicopter takes off from the roof of a building that is 200 feet above the ground. The altitude of the helicopter increases by 150 feet each minute.

(a) Use a formula to express the altitude of a helicopter as a function of time. (Let t be the time in minutes since takeoff and A the altitude in feet.) A =

(b) Express using functional notation the altitude of the helicopter 270 seconds after takeoff. A( )

Calculate that value. (Round your answer to the nearest foot.)