Since the time taken by the ball to reach its maximum height depends on the initial vertical speed only so the height from which it is launched makes no difference.
We know that,
the acceleration of gravity = 32.2 ft/s²
so every second, the ball will lose 32.2 ft/s of its upward speed and ultimately stop rising when its vertical speed has reached to zero.
So the ball will attain its maximum height in 3.42 seconds after the launch.