Question

A tank with rectangular base and rectangular sides, open at the top is to be constructed, so that its depth is 2 m and volume is 8 m³. If building of tank cost Rs 70 Per sq m for the base and Rs 45 per sq m for sides. What is the cost of least expensive tank ?

Answer 1

Let x m be the length, y m be the breadth and h = 2 m be the depth of the tank. Let Rs H be the total cost for building the tank. Now, given that h = 2 m and volume of tank = 8 m³ .

Also, area of the rectangular base of the tank 

= length x breadth = xy m² 

and the area of the four rectangular sides 

= 2 (length + breadth) x height 

= 2 (x + y) x 2 = 4(x + y ) m²