A horizontal thrown projectile

This problem requires a little bit of imagination. Look at the question carefully it says the projectile was thrown horizontally , so the next think comes to mind if it was thrown horizontally then it would remain in x axis forever creating an angle of zero degree. This seems suspicious! Right? So there must be something we are missing in y axis, what actually happening is the projectile somewhat represents a falling object from the edge of a cliff of a mountain with zero initial velocity in y axis.

$\tan 30 = \frac{v_{y}}{v_{x}}$

$v_{y}=gt$

$v_{x}=30$ remains unchanged in x axis

$\tan 30 = \frac{gt}{30}$

$\therefore t = \sqrt{3}$