Question

The cost of paint is Rs. $60$ per kilogram. A kilogram of paint covers $20d{m}^2$. How much will it cost to paint the outside of a cube having each side of $10$ dm ?

• A. Rs. $3000$
• B. Rs. $900$
• C. Rs. $1800$
• D. Rs. $360$

Answer 1

Answer: (C)

Rs. $1800$

Surface area of the cube $=6\times ($edge${)}^2$
$=(6\times 100)d{m}^2$
$=600d{m}^2$

Given, $20d{m}^2$ area is covered by $1$ kg paint.
$\therefore$ $600d{m}^2$ area is covered by $\frac{600}{20}$ kg
$=30$ kg paint.

$\therefore$ Cost of paint $=$ Rs. $(60\times 30)$ $=$ Rs. $1800$