the inner dimensions of a closed wooden box are 2m, 1.2 m and 0.75 m.The thickness of the wood is 2.5 cm, find the cost of wood reqd. to make the box, if 1 m3 wood costs Rs 5400.

Given, the inner dimension of closed wooden box = 2 m × 1.2 m × 0.75 m

So, volume of wooden box as per given inner dimensions = 2 m × 1.2 m × 0.75 m = 1.8 m³

Also, thickness of wood = 2.5 cm

Now, the length of outer wooden box = length of inner wooden box + thickness of wood

= length of inner wooden box + length increased on both sides of inner wooden box due to thickness of wood

= 2 m + 0.025 m  + 0.025 m

= 2.05 m

Similarly, breadth of outer wooden box = breadth of inner wooden box + thickness of wood = 1.2 m + 0.025 m  + 0.025 m  = 1.25 m

and height of outer wooden box = height of inner wooden box + thickness of wood = 0.75 m + 0.025 m  + 0.025 m = 0.8 m

Now, volume of wooden box as per outer dimensions = 2.05 m ×1.25 m × 0.8 m =  2.05 m³

So, net amount of wood required to construct the wooden box = volume of wooden box as per outer dimensions - volume of wooden box as per given inner dimensions =  2.05 m³ - 1.8 m³ = 0.25 m³

Given, cost of 1m³ of wood = Rs 5400

Therefore, cost of 247.75 m³ of wood = Rs 5400 × 0.25 = Rs 1350