Answer
Circular Paraboloid (axis is y-axis)
$x^{2}+z^{2}= y$
Work Step by Step
Given: $r(s,t)=\lt ssin(2t), s^{2}, scos(2t)\gt$
Write the vector equation in its equivalent parametric equations:
$x=ssin(2t) $, $y= s^{2}, $ and $z=scos(2t)$
Solving the first and third parametric equation yields:
$x^{2}+z^{2}= s^{2}sin^{2}2t +s^{2}cos^{2}2t$
$x^{2}+z^{2}= s^{2}(1)$
$x^{2}+z^{2}= y$
which represents as a equation of a Circular Paraboloid.