Vincen wrote:Hello M7MBA.
Here is a fast way to solve this PS question.
We know the following: $$\left(1\right)\ \ \ \ W\cdot L=30$$ $$\left(2\right)\ \ \ \ W\cdot H=60$$ $$\left(3\right)\ \ \ \ L\cdot H=72$$ Now, let's calculate the volumen squared, that is to say, $$V^2=\left(W\cdot L\cdot H\right)^2=W\cdot W\cdot L\cdot L\cdot H\cdot H$$ $$=\left(W\cdot H\right)\cdot\left(W\cdot L\right)\cdot\left(L\cdot H\right)$$ $$=\left(60\right)\cdot\left(30\right)\cdot\left(72\right)$$ $$=129600.$$ $$\Rightarrow\ \ \ V=\sqrt{129600}$$ $$\Rightarrow\ \ \ V=360.$$ Therefore, the correct answer is the option E.
Nice approach.
Just one suggestion:
Rather than calculate the product of 60, 30 and 72, break the factors into perfect squares, as follows:
V² = 30 * 60 * 72
V² = 30 * 30 * 2 * 2 * 36
V = √(30*30) * √(2*2) * √(6*6)
V = 30*2*6 = 360.
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