Answer
$[4,\infty)$
See the figure below.
Work Step by Step
Since the right boundary of the given inequality involves "greater than or equal", then the interval notion will have a bracket on left and paranthesis on right.
Hence, the given inequality can be written as $[4,\infty)$.
To graph, plot a solid dot at $x=4$, then shade the region from 4 till $\infty$.
See the figure below.
