# The students of a Vidyalaya were asked to participate in a competition for making and decorating penholders in the shape of a cylinder with a base, using cardboard. Each penholder was to be of radius 3 cm and height 10.5 cm. - Mathematics

The students of a Vidyalaya were asked to participate in a competition for making and decorating penholders in the shape of a cylinder with a base, using cardboard. Each penholder was to be of radius 3 cm and height 10.5 cm. The Vidyalaya was to supply the competitors with cardboard. If there were 35 competitors, how much cardboard was required to be bought for the competition?

["Assume "pi=22/7]

#### Solution

Radius (r) of the circular end of cylindrical penholder = 3 cm

Height (h) of penholder = 10.5 cm

Surface area of 1 penholder = CSA of penholder + Area of base of penholder

= 2πrh + πr2

=[2xx22/7xx3xx10.5+22/7xx(3)^2]cm^2

=(132xx1.5+198/7)cm^2

=(198+198/7)cm^2

=1584/7cm^2

"Area of cardboard sheet used by 1 competitor "=1584/7cm^2

Area of cardboard sheet used by 35 competitors

=(1584/7xx35)cm^2=7920cm^2

Therefore, 7920 cm2 cardboard sheet will be bought.

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

NCERT Class 9 Maths
Chapter 13 Surface Area and Volumes
Exercise 13.2 | Q 11 | Page 217