How much cardboard is required to make 35 penholders in the shape of cylinders, each of radius 3 cm and height 10.5 cm ?

Explanation

To find out how much cardboard is required to make 35 penholders in the shape of cylinders, we need to calculate the surface area of one penholder and then multiply that by 35.

### Step-by-Step Solution:

1. **Identify the dimensions of the cylinder**:
- Radius (r) = 3 cm
- Height (h) = 10.5 cm

...