Solution:
the boll,
y = Vo t + ½ g t²
y = 18 t + ½ (-9.8) t²
and the second one,
y = Vo t + ½ g t²
y = 30(t – 0.735) + ½ (-9.8)(t - 1.0.735)²
the stone and the ball will pass each other if,
y = y
18 t + ½ (-9.8) t² = 30(t – 0.73) + ½ (-9.8)(t - .0.73)²
t = 1.8196 sec
y = 18 t + ½ (-9.8) t²
y = 18(1.8196) + ½ (-9.8)(1.8196)²
y = 16.5292 m above initial point
Thus, this the required solution.