Carcass wrote:
The interior of a rectangular carton is designed by a certain manufacturer to have a volume of x cubic feet and a ratio of length to width to height of 3:2:2. In terms of x, which of the following equals the height of the carton, in feet?
A. \(\sqrt[3]{x}\)
B. \(\sqrt[3]{\frac{2x}{3}}\)
C. \(\sqrt[3]{\frac{3x}{2}}\)
D. \((\frac{2}{3})(\sqrt[3]{x})\)
E. \((\frac{3}{2})(\sqrt[3]{x})\)
The interior of a rectangular carton has a ratio of length to width to height of 3:2:2. Let 3k = the length of the carton
Let 2k = the width of the carton
Let 2k = the height of the carton
Note: Our goal is to find an equivalent value to 2k (the height of the carton)Note: This guarantees that the ratio of length to width to height of 3:2:2
The carton's volume is x. Volume of carton = (length)(width)(height)
So, we can write:
(3k)(2k)(2k) = xSimplify: \(12k^3 = x\)
Divide both sides by 12 to get: \(k^3 = \frac{x}{12}\)
Take the cube root of both sides to get: \(k = \sqrt[3]{\frac{x}{12}}\)
Multiply both sides of the equation by 2 to get: \(2k = 2\sqrt[3]{\frac{x}{12}}\)
Check the answer choices.....\(2\sqrt[3]{\frac{x}{12}}\) is not among them.
So it looks like we need to find an equivalent way to express \(2\sqrt[3]{\frac{x}{12}}\)
Since \(2= \sqrt[3]{8}\), we can write: \(2\sqrt[3]{\frac{x}{12}} = (\sqrt[3]{8})(\sqrt[3]{\frac{x}{12}})= \sqrt[3]{\frac{8x}{12}}= \sqrt[3]{\frac{2x}{3}}\)
Answer: B