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 heigh 105. 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 ?

The students of a Vidyalya were asked to participate in a competition for maiking and decorating pen holders in the shape of a cylinder with a base, using carboard. Each penholder was to be of radius 3 cm and height 10.5 cm. The Vidhaly was to supply the competittors with cardboard. If there were 35 competitiors, how much carboard was required to be bought for the competition ?

Shanti Sweets Stall was placing an order for making cardboard boxes for packing their sweets. Two sizes of boxes were required. The bigger of dimensions 25cmxx20xx5cm and the smaller of dimensions 15 cmxx12xx5cm. For all the overlaps, 5% of the total surface area is required extra. If the cost of the cardboard is Rs 4 for 1000cm^(2) , find the cost of cardboard required for supplying 250 boxes of each kind.

Rachel, an engineering student, was asked to make a model shaped like a cylinder with two cones attached at its two ends by using a thin aluminum sheet. The diameter of the model is 3 cm and its length is 12 cm . If each cone has a height of 2cm , find the volume of air contained in the model that Rachel made . ( Assume of outer and inner dimensions of the model to be nearly the same .