The students of a Vidyalaya were asked to participate in a competition for making and decorating pen holders in the shape of a cylinder with a base, using cardboard. Each pen holder 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?
Solution
Radius of circular end of cylinder pen holder = 3 cm
Height of pen holder = 10.5 cm
Surface area of 1 pen holder =`"CSA of penholder+Area of base of SA of 1 penholder"= 2pirh+pir^2`
`2pirh+pir^2`
= `2xx3.14xx3xx10.5+3.14138`
= `132xx1.5+198/7cm`
=`198+198/7cm^2`
=`1584/7cm^2`
Area of car board sheet used by 1 competitor = `1584/7 cm^2`
Area of car board sheet used by 35 competitors=`1584/735cm^2=7920cm^2`
