Surface Areas & Volumes | Exercise 13.2 | Q5

Question 5: A cylindrical pillar is 50 cm in diameter and 3.5 m in height. Find the cost of painting the curved surface area of the pillar at the rate of Rs.12.50 per m².

Explanatory Answer | Exercise 13.2 Q5

Height of the cylinder = 3.5 m
Diameter of the cylinder = 50 cm
So, its radius = 25 cm = \\frac{25}{100}) m = \\frac{1}{4}) m

Curved surface area of cylinder = 2πrh
Take π = \\frac{22}{7})

Curved surface area of cylinder = 2 × \\frac{22}{7}) × \\frac{1}{4}) × 3.5
= \\frac{22}{4}) = 5.5 m²

Cost of painting at the rate of Rs.12.50 per m² = 5.5 × 12.5
= Rs.68.75

Exercise 13.1 | Surface Area of Cubes & Cuboids

1. Class 9 Exercise 13.1 Question 3 | Height of hall ▶
2. Class 9 Exercise 13.1 Question 6 | TSA of Herbarium ▶
3. Class 9 Exercise 13.1 Question 7 | Shanti Sweets ▶

Exercise 13.2 | Surface Area of Cylinders

1. Class 9 Exercise 13.2 Question 3 | CSA TSA of Metal Pipe ▶
2. Class 9 Exercise 13.2 Question 4 | Roller & Playground ▶
3. Class 9 Exercise 13.2 Question 9 | Cylindrical Petrol Tank ▶
4. Class 9 Exercise 13.2 Question 10 | CSA of Decorative Lampshade ▶

Exercise 13.3 | Surface Area of Cones

1. Class 9 Exercise 13.3 Question 5 | Length of Tarpaulin 3 m wide ▶
2. Class 9 Exercise 13.3 Question 8 | Cost of painting conical barricades ▶

Exercise 13.4 | Surface Area of Spheres & Hemispheres

1. Class 9 Exercise 13.4 Question 8 | Outer CSA of hemispherical bowl ▶
2. Class 9 Exercise 13.4 Question 9 | Surface area of sphere & Cylinder ▶