A cylindrical pillar is 50 cm in diameter and 3.5 m in height. Find the cost of painting the curved surface of the pillar at the rate of ₹12.50 per m².

Solution:

Given: The diameter of the cylindrical pillar is 50 cm and its height is 3.5 m and the rate of painting is ₹12.50 per m^²

The curved surface area of a right circular cylinder of base radius r and height h is 2πrh.

Height(h) of the pillar = 3.5 m

Radius(r) = diameter/2 = 50/2 cm = 25 cm = 0.25 m

Now, curved surface area of the pillar = 2πrh

= 2 × 22/7 × 0.25 m × 3.5 m

= 5.5 m²

We can calculate the cost of painting by multiplying the curved surface area of the pillar and the rate of painting per meter square.

Cost of painting the curved surface area at ₹12.50 per m^² = 12.50 × 5.5

= ₹ 68.75

Thus, cost of painting the curved surface of the pillar is ₹ 68.75.

☛ Check: Class 9 Maths NCERT Solutions Chapter 13

Video Solution:

A cylindrical pillar is 50 cm in diameter and 3.5 m in height. Find the cost of painting the curved surface of the pillar at the rate of ₹ 12.50 per m².

Class 9 Maths NCERT Solutions Chapter 13 Exercise 13.2 Question 5

Summary:

It is given that there is a cylindrical pillar which is 50 cm in diameter and 3.5 m in height. We have found that the cost of painting the curved surface of the pillar is ₹ 68.75.

☛ Related Questions:

• Curved surface area of a right circular cylinder is 4.4 m². If the radius of the base of the cylinder is 0.7 m, find its height.
• The inner diameter of a circular well is 3.5 m. It is 10 m deep. Find i) Its inner curved surface area ii) The cost of plastering this curved surface at the rate of ₹40 per m².
• In a hot water heating system, there is a cylindrical pipe of length 28 m and diameter 5 cm. Find the total radiating surface in the system.
• Find i) The lateral or curved surface area of a closed cylindrical petrol storage tank that is 4.2 m in diameter and 4.5 m high. ii) How much steel was actually used, if 1/12 of the steel actually used was wasted in making the tank?