Question 36

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waecmaths question: 

What is the length of an edge of a cube whose total surface is X cm2 and whose volume is $\tfrac{x}{2}c{{m}^{2}}$

Option A: 

3

Option B: 

6

Option C: 

9

Option D: 

12

waecmaths solution: 

$\begin{align}  & \text{Total surface of a cube }=6{{l}^{2}}={{X}^{2}} \\ & Volume=V={{l}^{3}}=\frac{x}{2}cm \\ & \frac{V}{A}=\frac{{{l}^{3}}}{6{{l}^{2}}}=\frac{\tfrac{x}{2}}{x} \\ & \frac{l}{6}=\frac{1}{2} \\ & l=\frac{6}{2}=3cm \\\end{align}$

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