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 ₹ 5 per m²
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Answer 1

Length l=12m

Breadth b=9m

Height h=4m

⇒ Total surface of the tank =2(l×b+b×h+h×l)

=2(12×9+9×4+4×12)

=2×(108+36+48)

=192×2

=384m

2

⇒ Length of the sheet required =

2

384

m

=192m

∴ Cost of the sheet =192×5

=960

∴ Total cost of the sheet =Rs.960.

Hence, the answer is 960.

Answer 2

Length (l) of iron tank = 12m

Breath (b) of iron tank = 9m

Height (h) of iron tank = 4m

(S.A) of these walls is given as

S.A=2(lb+bh+hl)S.A=2(lb+bh+hl)

So, substitute the given values in above equation we have,

⇒S.A=2(12×9+9×4+4×12)⇒

S.A=2(108+36+48)

=2(192)=384m2

⇒S.A=2(12×9+9×4+4×12)

⇒S.A=2(108+36+48)

=2(192)=384m2

Now it is given that the sheet is 2 m wide.

So, length of the sheet required to make a closed iron tank =384 m22 m=192 m=384 m22 m=192 m

Now it is also given that the cost of iron sheet is Rs. 5 per meter sheet.

So, the total cost of iron sheet to make a closed iron tank =192×5=960 Rs.=192×5=960 Rs.

So, this is the required answer.