(1 point) A ball is thrown upward from the top of a building 310 feet tall.

(1 point) A ball is thrown upward from the top of a building 310 feet tall. The height of the ball is described by the function h(t)=−16t^2+24t+310, where t is in seconds and t=0 corresponds to the moment the ball is thrown. 

a) Determine for what value of t the ball reaches the maximum height and determine this maximum height. 

t= ?

 and maximum height = ?

b) Determine when the ball reaches the ground. 

t= ?

please help answer the ? question