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


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