Question

Gravity on the moon is about one- sixth of gravity on Earth. An astronaut standing on a tower 20 eet above the moon's surface throws a ball upward with a velocity of 30 feet per second. The height of the all at any time t (in seconds) is h(t) = -2.67t^2 + 30t + 20. To the nearest tenth of a second, how long will it take for the ball to hit the ground?