Question

A company makes a metallic block having square bases with volume $640$ $c{m}^3$, and height $10$ cm. If Robin wants to paint the block with the paints at the rate of Rs $15$ per $c{m}^2$, then find the cost of painting Robin has to pay.

• A. Rs $5680$
• B. Rs $6595$
• C. Rs $6720$
• D. Rs $6690$

Answer 1

The correct option is C Rs $6720$

The volume of block $=640c{m}^3$

and height of block $=10cm$

so, Area of the square base will be $=64c{m}^2$

Side of the base will be $\sqrt{64}=8$

So, dimensions of blocks are $8,8,10$.

and the total surface area will be:

$2(lb+bh+hl)=2\left(8\right(8)+10(8)+8(10\left)\right)$

$=2\left(224\right)$

$=448c{m}^2$

So, The cost of painting will be $=448\times 15=Rs6720$