Question

The density of a material in $SI$ units is $128kg{m}^{-3}$. In certain units in which the unit of length is $25cm$ and the unit of mass is $50g$, the numerical value of density of the material is

• A. $410$
• B. $640$
• C. $16$
• D. $40$

Answer 1

Answer: (D)

$40$

$\frac{128kg}{m^3}=\frac{125\left(50g\right)\left(20\right)}{\left(25cm{)}^4\right(4{)}^3}$
$=\frac{128}{64}\left(20\right)units$
$=40units$.