Question

a closed iron tank 12m long, 9m wide,4m deep is to be made. determine the cost of iron sheet used at the rate of Rs 5 per meter sheet, sheet being 2m wide?

Answer 1

Given that  length of the closed iron tank = 12 m.

Breadth of the closed iron tank = 9 m

The height of the closed iron tank = 4 m.

Total Surface Area of the tank = 2[lb + bh + hl]
= 2[12×9+9×4+4×12] = 384 $m^{2}$

Area of the rectangular iron sheet = 384 $m^{2}$
so that  length × breadth = 384 $m^{2}$

But breadth of sheet = 2 m (given)

∴  length = 384 / 2 = 192 m .

Given that cost of iron, the sheet used at the rate of Rs 5 per metre.
The total cost of the sheet = Rs. (192 × 5) = Rs. 960.

Hope I helped you! :)

Answer 2

Surface area of tank = 2x(12x9 + 9x4 + 4x12)
                                  = 2x (108 + 36 +48)
                                  = 2 x 192
                                  =384 $m^2$
Rate=Rs.5/2metre 
So, total cost = 384*5/2
                      =     1920/2
                      =  960

Ans: Rs. 960