Question

Find the volume of wood required for making the closed box with internal dimensions 20 cm by 12. 5 cm by 9. 5 cm.. thick of wood =1. 25 cm

Answer 1

Given outer length = 10 cm
Outer breadth = 8 cm
Outer height = 7 cm
Outer volume = length × breadth × height
= 10 × 8 × 7 = 560 cm3
Thickness of wooden box, w = 1 cm
Inner length = l – 2w = 10 – 2 = 8 cm
Inner breadth = b – 2w = 8 – 2 = 6 cm
Inner height = h – 2w = 7 – 2 = 5 cm
Outer volume = 8 × 6 × 5 = 240 c m3
Volume of wood used = outer volume – inner volume
 = 560 – 240 = 320 cm3
Given cost of 1 cm3 of wood = Rs 2
Hence the total cost of wood required = Rs 2 × 32
= Rs 640

Answer 2

volume of outer cuboid=lbh
                                     =2375
similarly v of inner cuboid =2003.9
volume of wood required to make the box=2375-2003.9
                                                                   =371.1