What is the standard deviation of a set of numbers: 5, 8, 12, 15, 18?
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What is the surface area of a rectangular prism with a length of 6 units, width of 4 units, and height of 5 units?
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What is the equation of a hyperbola with a horizontal transverse axis, centered at the origin, vertices at (+/- 3, 0), and asymptotes with slopes of +/- 1/2?