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?

Explanation

To find the amount of cardboard required for the penholders, we need to calculate the surface area of one cylindrical penholder and then multiply it by the number of competitors. Here’s a step-by-step solution:

### Step 1: Identify the dimensions of the penholder
- **Radius (r)** = 3 cm
- **Height (h)** = 10.5 cm

### Step 2: Calculate the surface area of one penholder
Since the penholder is open from the top, the surface area (SA) consists of the curved surface area (CSA) and the area of the base.
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