Question

A vessel of conical shape of radius 14cm and slanted height 20cm is to be coloured. What is the cost of painting at a rate of ₹2/cm^2? (Take π = \(\frac{22}{7}\))

(a) ₹1540

(b) ₹1660

(c) ₹1760

(d) ₹1500

The question was asked in an internship interview.

My question is from Surface Area of a Right Circular Cone topic in chapter Surface Areas and Volumes of Mathematics – Class 9

Answer 1

The correct option is (c) ₹1760

For explanation: We know that curved surface area of We know that the curved surface area of a cone = πrl

For the given conical vessel, r = 14cm and l = 20cm (given)

Hence, curved surface area of vessel = πrl

= \(\frac{22}{7}\) * 14 * 20

= 880cm^2

Now, the cost of painting 1cm^2 area = ₹2

Then the cost of painting 880cm^2 area = 880*2

= ₹1760.