2. 50 square stone slabs of equal size were needed to cover a floor area of 72 sq. m. The length of each stone slab is :

A. 102 cm B. 120 cm C. 201 cm D. 210 cm

Answer Answer: Option B Explanation: Area of each slab = (^{72}⁄_{50}) m^{2} = 1.44 m^{2}.
Length of each slab = $\sqrt{\mathrm{1.44}}$ m = 1.2 m = 120 cm.

3. The perimeters of five squares are 24 cm, 32 cm, 40 cm, 76 cm and 80 cm respectively. The perimeter of another square equal in area to the same of the areas of these squares is :

A. 31 m B. 62 m C. 124 m D. 961 m

Answer Answer: Option C Explanation: The sides of the five squares are (^{24}⁄_{4}) (^{32}⁄_{4}) (^{40}⁄_{4}) (^{76}⁄_{4}) (^{80}⁄_{4}) ie. 6 cm, 8 cm, 10 cm, 19 cm, 20 cm.
Area of the new square = [6^{2} + 8^{2} + (10)^{2} + (19)^{2} + (20)^{2}].
= (36 + 64 + 100 + 361 + 400) cm^{2} = 961 cm^{2}.
Side of the new square = $\sqrt{\mathrm{961}}$ cm = 31 cm.
Perimeter of the new square = (4 * 31) cm = 124 cm.

5. The length and breadth of the floor of the room are 20 feet and 10 feet respectively. Square tiles of 2 feet length of different colours are to be laid on the floor. Black tiles are laid in the first row on all sides. If white tiles are laid in the one-third of the remaining and blue tiles on the rest, how many blue tiles will be there ?

A. 16 B. 24 C. 32 D. 48

Answer Answer: Option A Explanation: Area left after laying black tiles = [(20 - 4) * (10 - 4)] sq. ft = 96 sq. ft.
Area under white tiles = (^{1}⁄_{3} * 96) sq. ft = 32 sq. ft.
Area under blue tiles = (96 - 32) sq. ft = 64 sq. ft.
Number of blue tiles =^{64}⁄_{(2 * 2)} = 16.