Q. 135.0( 5 Votes )

# A wooden toy is in the form of a cone surmounted on a hemisphere. The diameter of the base of the cone is 16 cm, and its height is 15 cm. Find the cost of painting the toy at Rs. 7 per 100 cm^{2}.

Answer :

**Concept Used:** Surface Area of Hemisphere = 2πr^{2}

Curved Surface Area of cone = πrl

Lateral length of the cone = √(h^{2} + r^{2})

Where, r = radius of hemisphere and cone, and l = slant height of the cone.

**Given:**

The radius of the hemisphere = 8 cm

Height of the cone = 15 cm

**Explanation:**

Let us find the lateral length of cone first,

Lateral length of the cone = √(h^{2} + r^{2}) = √(15^{2} + 8^{2}) = 17 cm

The total curved surface area of the toy = 2πr^{2} + πrl

⇒ The total curved surface area of the toy

⇒ The total curved surface area of the toy = 829.714 cm^{2}

Cost of painting the toy at Rs. 7 per 100 cm^{2} = Rs. 58.08

**Hence, the cost of painting the toy is Rs. 58.08.**

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