How many cubic centimetres of iron are there in an open box whose external dimensions are 36cm, 25cm and 16.5cm, the iron being 1.5cm thick throughout? If 1 cubic cm of iron weighs 15g, find the weight of the empty box in kg.

Answer

`3960 cm^(3), 59.4 kg`

Explanation

External volume of the box `= (36 xx 25 xx (33)/(2)) cm^(3) = 14850 cm^(3)`
Internal volume of the box `= (33 xx 22 xx 15) cm^(3) = 10890 cm^(3)`
Volume iron in the box `= (14850 - 10890) cm^(3) = 3960 cm^(3)`
Weight of the empty box `= (3960 xx 15 xx (1)/(1000)) kg = 59.4 kg`