Question

The external dimensions of a closed wooden box are $10cm\times 8cm\times 7cm$. Thickness of wood is 1cm. Find the total cost of wood required to make box if the cost of wood is Rs.2 per cubic centimeter.

• A. Rs. 540
• B. Rs.620
• C. Rs.640
• D. Rs.756

Answer 1

The correct option is C Rs.640


External dimensions are $L=10cm,B=8cm,H=7cm$
Since the thickness of wood is $1cm$,
Internal dimensions are $l=8cm,b=6cm,h=5cm$
Required volume of wood = External volume - Internal volume
= $(L\times B\times H)-(l\times b\times h)$
= $(10\times 8\times 7)-(8\times 6\times 5)$
= 560 - 240
= 320 cm${}^3$
Thus, the required cost of wood
= Rs.2/cm${}^3\times 320c{m}^3$
= Rs.640
Hence, the correct answer is option (c)