Initial speed u = 17 m/s
1. u^2/(2g) = 17^2/(2 * 9.8) = 289/19.6 = 14.7 m
2.) 2u/g = 2 * 17/9.8 = 3.47 second
Note: After time u/g, it reaches to maximum height. It takes u/g to fall from maximum height to the point of throw. Therefore, in total it is in the air for 2u/g time.