If the radius of the base of a right circular cylinder is halved, keeping the height same, what is the ratio of the volume of the new cylinder to that of the original one?

1. 1 : 2

2. 1 : 4

3. 1 : 8

4. 4 : 1

The radii of two cylinders are in the ratio 2 : 3 and their heights are in the ratio 5 : 3. The ratio of their curved surface areas is :

1. 2 : 5

2. 8 : 7

3. 10 : 9

4. 16 : 9

Two rectangular sheets of paper each 30 cm × 18 cm are made into two right circular cylinders, one by rolling the paper along its length and the other along the breadth. The ratio of the volumes of the two cylinders, thus formed, is :

1. 2 : 1

2. 3 : 2

3. 4 : 3

4. 5 : 3