Perimeter = 2 x (36 + 21 )m = 144 m
∴ Number of flagstaffs = 144 / 3

Correct Option: B

Perimeter = 2 x (36 + 21 ) m = 144 m
∴ Number of flagstaffs = 144 / 3 = 38

Let breadth = y meters,
Then, length = 2y meters

∴ Diagonal = √y² + (2y)²
= √5y² meters

So, √5y² = 9 √5

∴ y= 9

Correct Option: B

Let breadth = y meters,
Then, length = 2y meters

∴ Diagonal = √y² + (2y)²
= √5y² meters

So, √5y² = 9 √5
∴ y= 9

Thus, breadth = 9 m and length = 18 m
∴ Perimeter = 2 (18 + 9) m = 54m.

Length = (40 x 10 ) dm = 400 dm.
Breadth = (15 x 10 ) dm = 150 dm.

Area of veranda = (400 x 150 ) dm²
Area of one stone = (6 x 5 ) dm²

Correct Option: B

Length = (40 x 10 ) dm = 400 dm.
Breadth = (15 x 10 ) dm = 150 dm.

Area of veranda = (400 x 150 ) dm²
Area of one stone = (6 x 5 ) dm²

∴ Required number of stones = (400 x 150) /(6 x 5) = 2000

Let each side = x cm
Then, (x + 4 )² - x² = 60

Correct Option: D

Let each side = x cm
Then, (x + 4 )² - x² = 60
⇒ x ² + 8x + 16 - x² = 60
∴ x = 5.5 cm

Let area 100 m²
Then, side = 10 m

New side = 125 % of 10
= (125/100) x 10)
= 12.5 m

New area = 12.5 x 12.5 m²
=(12.5)² sq. m

Correct Option: D

Let area 100 m²
Then, side = 10 m

New side = 125 % of 10
= (125/100) x 10
= 12.5 m

New area = 12.5 x 12.5 m²
=(12.5)² sq. m

∴ Increase in area = (12.5)² - (10)² m²
= 22.5 x 2.5 m²
=56.25 m²

% Increase = 56.25 %