Answer:
10.25 ft
Step-by-step explanation:
According to the law of conservation of energy, the initial kinetic energy of the ball when it is thrown upward is entirely converted into gravitational potential energy when the ball reaches its maximum height. So we can write:

where
m is the mass of the ball
v = 4 ft/s is the initial speed
g = 32 ft/s^2 is the acceleration due to gravity
is the change in height of the ball
Re-arranging the equation, we find

And since the ball was thrown from a heigth of 10 feet, the maximum height reached is
h = 10 ft + 0.25 ft = 10.25 ft