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 ₹ 210 per 100 m².

Solution:

The slant height of the conical tomb is 25 m and the base diameter is 14 m. 

The curved surface area of a right circular cone of base radius(r) and slant height(l) is πrl

Slant height, l = √r² + h², where h is the height of the cone.

Diameter, d = 14 m

Radius, r = 14/2 m = 7 m

Slant height, l = 25 m

Curved surface area = πrl

= 22/7 × 7 m × 25 m

= 550m²

Cost of the whitewashing at ₹ 210 per 100 m²

= (210/100) × 550 = ₹ 1155

Thus, the cost of whitewashing the conical tomb is ₹1155.

☛ Check: NCERT Solutions for Class 9 Maths Chapter 13

Video Solution:

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 ₹ 210 per 100 m².

Class 9 Maths NCERT Solutions Chapter 13 Exercise 13.3 Question 6

Summary:

It is given that the slant height and base diameter of a conical tomb is 25 m and 14 m respectively. The cost of white-washing its curved surface at the rate of ₹ 210 per 100 m² is ₹1155.

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