Answer:
Time, t = 1.875 seconds
Explanation:
It is given that,
Initial velocity of the ball, u = 30 ft/s
DeSean throws a ball from a platform that is at ground level. The equation of motion when an object is thrown vertically upward is given by the following equation as :

Here, h = 0 since, the ball is thrown up at the ground level. We have to determine the time when the ball be in air. The quadratic equation becomes :

t = 1.875 seconds
So, the ball be in air for 1.875 seconds. Hence, this is the required solution.