On a television program, a comedian tosses a watermelon from the top of a five-story building. The height of the watermelon as it falls is given by the function below, where is the number of seconds since the watermelon was tossed
h（土）=－1682+16t+60
The quadratic expression in the function can be factored as shown.
h (t) = -4 (2t + 3) (2t - 5)
How many seconds does the watermelon fall before it hits the ground?