Option 2 : 4.2 m2

**Given:**

Radius od cylinder = radius of base of cone = 35 cm

Height of cylinder = 1.5 m

Slant height of cone = 0.5 m

Diameter of circular hole = 20 cm

**Formula used:**

Curved surface area of cylinder =** **2πRh

Letral surface area of cone = πRl

Area of circle = πr^{2}

Where,

R = Radius of cylinder and base of circle

h = height of cylinder

r = radius of circle

**Calculation:**

Let, total surface area = A

Digram according to the given conditions is shown in figure

Total surface area (A) = area of base of cylinder + area of curved surface of cylinder + area of a curved surface of cone - area of circular opening.

\(A \ = \ π(\frac{35}{100})^2\ + \ 2π\frac{35}{100}\times 1.5\ + π(\frac{35}{100})\times 0.5\ -\ π(\frac{10}{100})^2 \)

⇒ A = π(0.35)^{2} + 3π(0.35) + 0.5π(0.35) - π(0.1)^{2}

⇒ A = 1.3375π

⇒ A = 4.2 m^{2}

Hence, total surface area of postbox is 4.2 m2