# Twenty Cylindrical Pillars of the Parliament House Are to Be Cleaned. If the Diameter Of Each Pillar is 0.50 M and Height is 4 M. What Will Be the Cost of Cleaning Them at the Ra - Mathematics

Twenty cylindrical pillars of the Parliament House are to be cleaned. If the diameter of each pillar is 0.50 m and height is 4 m. What will be the cost of cleaning them at the rate of Rs. 2.50 per square metre?

#### Solution

Diameter of each pillar=0.5m

Radius of each pillar (r) a/2= 0.5/2=0.25m

Height of each pillar=4m

Curved surface area of each pillar=2pirh

= 2xx3.14xx0.25xx4m^2

= 44/7 m^2

Curved surface area of 20 pillars= 20xx44/7m^2

Given, cost of cleaning= Rs.2.50 per square meter

∴Cost of cleaning 20 pillars = Rs.2.50xx20xx44/7

=Rs.314.28.

Concept: Surface Area of Cylinder
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#### APPEARS IN

RD Sharma Mathematics for Class 9
Chapter 19 Surface Areas and Volume of a Circular Cylinder
Exercise 19.1 | Q 11 | Page 8

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