Find the area of the circle, length of whose circumference is equal to the sum of the lengths of the circumferences with radii 15 cm and 13 cm.

A piece of wire of length 108 cm is bent to form a semicircular arc bounded by its diameter. Find its radius and area enclosed.

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