Question

The height of a wall is six times its width and the length of the wall is seven times its height. If the volume of the wall be $16128$ cu. m, its width:

• A. 4 m
• B. 4.6 m
• C. 5 m
• D. 6 m

Answer 1

The correct option is A 4 m

let the width of wall be ${}^{\prime }{x}^{\prime }$ metres

height $=5\times$ weidth $-6x$ metres

length $=7\times$ height $=7\times \left(6x\right)=\left(42x\right)$ metres.

$\therefore volume=length\times height\times width$

$\Rightarrow 16128m^2=\left(42x\right)\left(6x\right)\left(x\right)m^3$

$\Rightarrow 16128=252x^3$

$\Rightarrow x^3=64$

$\Rightarrow x=9$

$\therefore$ width of wall $=x$ metres $=4m$