Question

A cuboidical in box is 20 cm by 30 cm by 40 cm. The cost of the tin sheet required to make 15 such boxes if the cost(in rupees) of tin sheet is Rs. 10 per sq. m. is ____ .

Answer 1

Dimension of cuboidal box $=20cm\times 30cm\times 40cm$

Here,

$l=20cm,b=30cm$ and $h=40cm$

Total surface area $=2(lb+bh+lh)$

$=2(20\times 30+30\times 40+20\times 40)$

$=2(600+1200+800)$

$=2\left(2600\right)$

$=5200c{m}^2$

$\therefore$ Surface area of $15$ box $=15\times 5200=78000c{m}^2$

$\Rightarrow$ Surface area of $15$ box in $m^2=\frac{78000}{10000}=7.8m^2$

$\Rightarrow$ Cost of tin sheet required to make $1$ box $=Rs.10m^2$

$\Rightarrow$ Total cost of the tin sheet required to make $15$ box $=Rs.(7.8\times 10)=Rs.78$