# 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. - Mathematics

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.

#### Solution

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

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

$= 2 \times (12 \times 9 + 9 \times 4 + 12 \times 4)$

$= 2 \times (108 + 36 + 48)$

$= 384 m^2$

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

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

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

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

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

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#### APPEARS IN

RD Sharma Class 8 Maths
Chapter 21 Mensuration - II (Volumes and Surface Areas of a Cuboid and a Cube)
Exercise 21.4 | Q 7 | Page 30