Question

9. Find

(i) & (ii) Solve questions first and second quickly

give me answer fast !​

Answer 1

Step-by-step explanation:

80 grml was used to make the tank

Answer 2

Given :-

• Diameter of petrol tank (d) = 4.2 m
• Height of petrol tank (h) = 4.5 m

To Find :-

• (i) Lateral or curved surface area of petrol tank ?
• (ii) How much steel was actually used if 1/12 of the steel actually used was wasted the tank ?

Solution :-

• As diameter of tank (d) is 4.2 m.
• Radius of tank (r) = d/2 = 4.2/2 = 2.1 m.

★ (i)

Finding curved surface area of petrol tank by using the formula of CSA of cylinder. As we know that,

• CSA of cylinder = 2πrh

• Putting all values we get,

➻ CSA (Petrol tank) = 2 × 22/7 × 2.1 × 4.5

➻ CSA (Petrol tank) = 2 × 22 × 0.3 × 4.5

➻ CSA (Petrol tank) = 44 × 1.35

➻ CSA (Petrol tank) = 59.4 m²

• Hence, lateral of curved surface area of closed cylindrical petrol storage tank is 59.4 m².

Now, finding total surface area of petrol tank by using the formula of TSA of cylinder. As we know that,

• TSA of cylinder = 2πr(r + h)

• Putting all values we get,

➻ TSA (Petrol tank) = 2 × 22/7 × 2.1(2.1 + 4.5)

➻ TSA (Petrol tank) = 2 × 22 × 0.3(6.6)

➻ TSA (Petrol tank) = 2 × 22 × 03. × 6.6

➻ TSA (Petrol tank) = 44 × 1.98

➻ TSA (Petrol tank) = 87.12 m²

• Hence, total surface area of closed cylindrical petrol storage tank is 87.12 m².

★ (ii)

• Let x m² steel was actually used in making the tank.

According to the question 1/12 of the steel actually used was wasted in making the tank.

Steel wasted ;

• 1/12

Steel used to making tank ;

• 11/12

Therefore,

• 11/12 of (Total steel used to make tank) = TSA of tank.

So,

➻ 11/12 × x = 87.12

➻ x = 87.12 × 12.11

➻ x = (87.12 × 12)/11

➻ x = 1045.44/11

➻ x = 95.04 m²

• Hence, 95.04 m² steel was actually used in making the closed cylindrical petrol storage tank.

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