Find the capacity of a closed rectangular cistern whose length is 8 m, breadth 6 m and depth 2.5 m.

Length of the cistern, l = 8 m

Breadth of the cistern, b = 6 m

Height (or depth) of the cistern, h = 2.5 m

∴ Capacity of the cistern

= Volume of the cistern

= l × b × h

= 8 × 6 × 2.5

= 120 m3

Also,

Area of the iron sheet required to make the cistern

= Total surface area of the cistern

= 2(lb + bh + hl)

= 2(8 × 6 + 6 × 2.5 + 2.5 × 8)

= 2 × 83

= 166 m2