Length of carpet = Total Cost / Rate
= 3600 / 30
= 120 m

Area of carpet = (120 x 75) / 100 m²
= 90 m²
∴ Area of the room = 90 m²

Correct Option: A

Length of carpet = Total Cost / Rate
= 3600 / 30
= 120 m

Area of carpet = (120 x 75) / 100 m²
= 90 m²
∴ Area of the room = 90 m²

Breadth of the room = Area /Length
= 90 / 15 m
= 6m

Let length = l and breadth = b
Then, area = lb

New length = 2l
and new breadth = b/2
∴ New area = ( 2l ) x (b/2) = lb

Correct Option: C

Let length = l and breadth = b
Then, area = lb

New length = 2l
And new breadth = b/2
∴ New area = ( 2l ) x (b/2) = lb

So, there is no change in area .

Altitude = √(13)² - (5)²
= √144 = 12m

Correct Option: C

Altitude = √(13)² - (5)²
= √144 = 12m

∴ Area of the triangle = (5 x 12 ) / 2 m²
= 30m²