A rocket is fired straight up. It contains two stages (Stage 1 and Stage 2) of solid rocket fuel that are designed to burn for 10.0 and 5.00 s, respectively, with no time interval between them. In Stage 1, the rocket fuel provides an upward acceleration of 15.0 m/s2. In Stage 2, the acceleration is 10.0 m/s2. Neglecting air resistance, calculate the maximum altitude above the surface of Earth of the payload and the time required for it to return to the surface. Assume the acceleration due to gravity is constant.

1) Calculate the maximum altitude. (Express your answer to two significant figures.)
2) Calculate time required to return to the surface (i.e. the total time of flight). (Express your answer to three significant figures.)