A standard DVD has a diameter of 12.0 cm, and a hole that is centered on the axis of symmetry and has a diameter of 1.50 cm. The DVD’s thickness is 1.2 mm, and it's mass is 17 g. If a (very thin) pin extending through the hole of the DVD suspends it in a vertical orientation, as shown in the figure, the DVD may oscillate about an axis parallel to the pin, rocking back and forth. How long does it take to complete 9 complete oscillations?