An oil funnel made of tin sheet consists of a 10 cm long cylindrical portion attached to a frustum of a cone. If the total height is 22 cm, diameter of the cylindrical portion is 8 cm and the diameter of the top of the funnel is 18 cm, find the area of the tin sheet required to make the funnel.

Upper radius of frustum (r₁) = 9 cm and lower radius of frustum (r₂) = 4 cm
Therefore, the radius of cylindrical part = 4 cm
Height of frustum (h₁) = 22 – 10 = 12 cm
Height of cylindrical part (h₂) = 10 cm
Slant height of frustum (l) = √(r₁ – r₂)² + h² = √(9 – 4)² + 12² = 13 cm
Area of required tin = Curved surface area of frustum + curved surface area of cylindrical part = π(r₂ + r₂)l + 2πr₂h₂
= 22/7 × (9 + 4) × 13 + 2 × 22/7 × 4 × 10
= 22/7 [169 + 80] = (22 × 249/7) = 782(4/7) cm²