Answer
Please see the work below.
Work Step by Step
We know that
$\omega=\sqrt{\frac{g}{r}}$..........eq(1)
Let x be the revolutions per minute required to simulate earth's gravity. Then radians per second conversion gives us
$\omega=\frac{x\times 2\pi}{60}$...........eq(2)
comparing eq(1) and eq(2), we obtain:
$\frac{x\times 2\pi}{60}=\sqrt{\frac{g}{r}}$
This can be rearranged as:
$x=\frac{60}{2\pi}\times \sqrt{\frac{g}{r}}$
We plug in the known values to obtain:
$x=\frac{60}{2\times 3.1416}\sqrt{\frac{9.8}{\frac{450}{2}}}$
$x=1.99\space revolutions \space \space per\space minute$