Question

One cubic meter of copper is melted and recast into a square cross- section bar $36m$ long. An exact cube is cut off from this bar. If $1$ cubic meter of copper costs $Rs108$, then the cost of this cube is

• A. $50$ paise
• B. $75$ paise
• C. $1$ rupee
• D. $1.50$ rupee

Answer 1

The correct option is A $50$ paise

Let the side of the rod is $x$ m.
Volume of rod=Volume of metal piece
$X\times X\times 36=1$
$X=\frac{1}{6}$
$\therefore$ exact cube of length=$\frac{1}{6}m$ can be cut.
Volume of cube=$(\frac{1}{6}{)}^3$
=$\frac{1}{216}{m}^3$
$1m^3$ copper cost=$Rs108$
$\therefore \frac{1}{216}{m}^3$ will cost=$\frac{108}{216}$
=$\frac{1}{2}$
=$50$ paise