The area of the four walls in a room is 120 m2. The length is twice the breadth. If the height of the room is 4 m, find the area of the floor.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 50 m2
The four walls of a room are two pairs of rectangles, so their total area is 2 × height × (length + breadth). This gives the sum of length and breadth; the condition “length is twice the breadth” then splits it.
\(2\times4\times(l+b)=120\), so \(l+b=15\) m
\(l=2b\), so \(3b=15\) and \(b=5\) m
\(l=2\times5=10\) m
Area of the floor \(=l\times b=10\times5=50\) m2