An iron box with external dimensions 60 cm, 40 cm, and 20 cm is made of 1 cm thick sheet. If 1 cm3 of iron weighs 50 gm, the weight of the empty box is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 416.40 kg.
The external dimensions of the box are:
Length = 60 cm
Width = 40 cm
Height = 20 cm
The external volume of the box = 60 × 40 × 20 = 48000 cm3
the thickness of the iron sheet is 1 cm
so
the internal dimensions are:
Internal length = 60 − 2 = 58 cm
Internal width = 40 − 2 = 38 cm
Internal height = 20 − 2 = 18 cm
Internal volume = 58 × 38 × 18 = 39672cm3
The volume of iron = External volume - Internal volume
⇒ 48000 − 39672 = 8328cm3
1 cm³ = 50 gm
Therefore,
Weight of the box = 8328 × 50 = 416400 grams = 416.4 kg