Question

$w=\frac{l}{8}$
$h=3w$
An engineer determined that a bridge he is designing has maximum stability when its length, $l$, width,$w$, and height,$h$, are defined by the equations above. If he wants to build a bridge with a height of $9$ meters, what should be the length of the bridge, in meters?

• A. $96$
• B. $24$
• C. $12$
• D. $8$

Answer 1

The correct option is B $24$

$w=\frac{l}{8}$ and $h=3w=\frac{3l}{8}$.
If $h=9$, then $l=\frac{8h}{3}=\frac{8\times 9}{3}=24m$.