Your answer would be the time in takes for carbon-14 to elapse 3 half-lives.
5730 • 3 = 17190
Surface area is the total area of the surface. A cube has 6 surface, and each surface is the same. Each surface is a 11 by 11 square. Therefore there will be 6 11in. x 11in. surfaces. The math would be 11x11x6 =726.