An open rectangular cistern when measured from outside is 1.35 m long, 1.08 m broad and 90 cm deep. It is made up of iron, which is 2.5 cm thick. Find the capacity of the cistern and the volume of the iron used.
Given,
External Dimensions of cistern = 1.35m × 1.08m × 90cm = 135cm × 108cm × 90cm
External volume of cistern = l × b × h = 135 × 108 × 90 = 1312200 cm3
Internal dimensions of cistern = length = 135 – (2.5 × 2) = 130 cm
Breadth = 108 – (2.5 × 2) = 103 cm
Height = 90 – 2.5 = 87.5 cm
∴ internal volume of cistern = 130 × 103 × 87.5 = 1171625 cm3
Volumeof iron used = (External volume – Internal volume)
= 1312200 – 1171625 = 140575 cm3