Each side of a triangle is doubled, the ratio of areas of the original triangle to the new (resulting) triangle is :

1. 1 : 1

2. 4 : 1

3. 1 : 4

4. 1 : 2

The perimeter of a rectangle is equal to the perimeter of a square. If each side of the square is 30 cm and length of the rectangle is 40 cm; the breadth of the rectangle is :

1. 5 cm

2. 16 cm

3. 15 cm

4. 20 cm

The external and internal radii of a ring shaped metal sheet are 10 cm and 8 cm respectively. The area of its one face, in terms of π is :

1. 36π cm²

2. 64π cm²

3. 100π cm²

4. 168π cm²

The adjacent sides of a rectangle are 20 cm and 24 cm. If its perimeter is equal to the circumference of a circle, the radius of the circle is :

1. 14 cm

2. 21 cm

3. 28 cm

4. 7 cm