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- Rs. 52.00 approx
- Rs. 39.20 approx
- Rs. 35.20 approx
- Rs. 23.94 approx

Option 3 : Rs. 35.20 approx

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**Given:**

Height of conical tank = 60 cm

Diameter of base = 64 cm

**Formula:**

Slant height (l), Height (h) and Radius (r)

Total surface area of cone = πrl + πr^{2}

**Calculation:**

Radius of base(r) = 64/2 = 32 cm

Using pythagoras theorem,

(slant height)^{2} = height^{2} + radius^{2}

Slant height = √(60^{2} + 32^{2}) = 68 cm

Total surface area of conical tank = π × 32 × 68 + π × 32^{2} = 10057.14 cm^{2} = 1.0057 m^{2}

**∴ Cost of painting tank from outside = 1.0057 × 35 = Rs. 35.20**.

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