17. Find the volume of wood required for makingthe closed box with int

1.	17. Find the volume of wood required for makingthe closed box with internal dimensions : 20 cmby 12.5 cm by 9.5 cm ; wood 1.25 cm thick.
Answer» 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 m3Volume of wood used = outer volume – inner volume = 560 – 240 = 320 cm3 Given cost of 1 cm3of wood = Rs 2 Hence the total cost of wood required = Rs 2 × 32= Rs 640

17. Find the volume of wood required for makingthe closed box with internal dimensions : 20 cmby 12.5 cm by 9.5 cm ; wood 1.25 cm thick.

Answer»

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 m3Volume of wood used = outer volume – inner volume

= 560 – 240 = 320 cm3

Given cost of 1 cm3of wood = Rs 2

Hence the total cost of wood required = Rs 2 × 32= Rs 640