Question

A closed iron tank 12 m long, 9 m wide and 4 m deep is to be made. Determine the cost of iron sheet used at the rate of Rs 5 per metre sheet, sheet being 2 m wide.

Answer 1

\[\text { A closed iron tank of dimensions 12 m long, 9 m wide and 4 m deep is to be made } . \]

\[\text { Surface area of the cuboidal tank = 2 } \times\text {  (length  }\times \text { breadth + breadth } \times\text {  height + length } \times \text { height) }\]

\[ = 2 \times (12 \times 9 + 9 \times 4 + 12 \times 4)\]

\[ = 2 \times (108 + 36 + 48)\]

\[ = 384 m^2 \]

\[\text { Also, the cost of an iron sheet is Rs 5 per metre and the sheet is 2 metres wide } . \]

\[\text { i . e . , area of a sheet = 1 m } \times 2 m = 2 m^2 \]

\[\text { So, the cost of 2  }m^2 \text { of iron sheet = Rs 5 }\]

\[\text { i . e . , the cost of 1 }m^2 \text { of iron sheet = Rs } \frac{5}{2}\]

\[ \therefore \text { Cost of 384  }m^2 \text { of iron sheet = 384 } \times \frac{5}{2} = \text { Rs } 960\]