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RD Sharma Solutions Class 9 Mathematics Solutions for Surface Area And Volume Of a Right Circular Cylinder Exercise 19.1 in Chapter 19 - Surface Area And Volume Of a Right Circular Cylinder

Question 2 Surface Area And Volume Of a Right Circular Cylinder Exercise 19.1

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 Rs 12.50 per m2.

Answer:

Height of cylindrical pillar (h) = 3.5 m

Radius of circular end of pillar ( r) = 50/2 cm = 25 cm = 0.25 m

[As radius = half of the diameter] and [1 m = 100 cm]

Curved surface area of cylindrical pillar = 2πrh

= 2 x 3.14 x 0.25 x 3.5

= 5.5

Curved surface area of cylindrical pillar is 5.5 m.

Find the cost:

Cost of whitewashing 1m2 is Rs 12.50 (Given)

Cost of whitewashing 5.5 m2 area = Rs. 12.50 x 5.5 = Rs. 68.75

Thus the cost of whitewashing the pillar is Rs 68.75.

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