Answer:
Step-by-step explanation:
The equation that models the height of the ball in feet as a function of time is

Where
is the initial height,
is the initial velocity and t is the time in seconds.
We know that the initial height is:
The initial speed is:

So the equation is:

The ball hits the ground when when
So

We use the quadratic formula to solve the equation for t
For a quadratic equation of the form

The quadratic formula is:

In this case

Therefore

We take the positive solution.
Finally the ball takes 2.47 seconds to touch the ground