can you please help?! physics! thanks?

Question

A ball is thrown vertically upward (assumed to be the positive direction) with a speed of 16.0 m/s from a height of 3.0 m.
(a) How high does the ball rise from its original position?
m
(c) How long does the ball take to hit the ground after it reaches its highest point?
s

Answer 1

(a) since v = 16.0 m/s, and v/g = t
s = 0.5g*t^2 =0.5v^2/g = 0.5*16.0^2/9.8 = 13.1m
Thus the ball may rise from its original position for 13.1m, a total height of 16.1m.
(c) Now 16.1 = 0.5g*T^2
T = sqrt(2*16.1/9.8) = 1.81(s)
Thus the ball take 1.81s to hit the ground after it reaches its highest point.