Answer:

The ball remains in the air for 2.86 seconds.
Step-by-step explanation:
A baseball is hit into the air, and its height above the ground is described by the function

Where H(t) represents the height of the ball t seconds after it is hit.
The ball remains in the air before it hits the ground.
When the ball hits the ground,

So,

The equation may be solved using the quadratic formula.

Where

So,

Since the time cannot be negative, discard the negative value and accept the positive value

Therefore, the ball remains in the air for 2.86 seconds.