Surface Areas & Volumes | Exercise 13.3 | Q6

Question 6: The slant height and base diameter of a conical tomb are 25 m and 14 m respectively. Find the cost of white-washing its curved surface at the rate of Rs.210 per 100 m².

Explanatory Answer | Exercise 13.3 Question 6

Step 1: Compute Curved Surface Area of Conical Tomb

Given Data: Slant height of the conical tomb, l = 25 m
Diameter of the conical tomb, d = 14 m
Radius of the conical tomb, r = \\frac{14}{2}) = 7 m

Curved surface area of the conical tomb = π × r × l
Take π =\\frac{22}{7})
Curved surface area of cone = \\frac{22}{7}) × 7 × 25
= 550 m²

Step 2: Compute Cost of White-Washing Conical Tomb

Cost of white-washing the conical tomb per 100 m² = Rs. 210
Cost of white-washing the conical tomb per m² = \\frac{210}{100})= Rs.2.1

Cost of white-washing the canvas at the rate of Rs.2.1 per m² = 550 × 2.1
= Rs. 1155

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 ▶