Final answer:
The maximum height of a projectile and the time to reach it or hit the ground can be determined using a quadratic equation representing height as a function of time. However, the provided formula seems to contain an error, preventing exact answers from being given.
Step-by-step explanation:
The function given for the height of the cannonball above the ground is h(t) = -4.912t2 + 24.5t + 7.9. To find the maximum height attained by the cannonball, one would need to complete the square or take the derivative of h(t) and set it to zero to find the time at which the maximum height occurs. Unfortunately, without the complete right formula for h(t), it's impossible to provide the exact maximum height and the times requested.
Typically, the maximum height of a projectile in free fall is achieved when the velocity is zero (at the top of the arc). The time it takes to reach maximum height can be found using the initial vertical component of the velocity and the acceleration due to gravity. The time to hit the ground would be when h(t) equals zero, and solving for t in the quadratic equation gives the answer, but again, this requires the corrected quadratic term in the formula.