Question

A Cuboidal fish tank has a length of 30 cm , 20 cm and a height of 20 cm . The tank is placed on a horizontal table and it is three - quarters full of water . Find the area of the tank which is in contact with water

Answer 1

Dimensions of Cuboidal fish tank:
     Length L = 30 cm.   Breadth = B = 20 cm.    Height = H = 20 cm
 
If the tank is 3/4 th full of water, it means that it is filled up to 3/4th of its height.

       So water is filled upto  h = 20 cm * 3/4 = 15 cm.

Surface area of the floor (base) of the tank
     = L * B = 30 * 20 = 600 cm²

Surface area of the walls of the tank up to height = h = 15 cm:
     = 2 L h  + 2 B h
     = 2 * 30 cm * 15 cm + 2 * 20 cm * 15 cm
     = 1500 cm²

Total surface area of the tank in contact with water
   = 600 + 1500
   = 2, 100 cm²