The sum of length breadth and height of a room is 19m The length of the diagonal is 11m Find he cost...........

Quantitative Aptitude ( CCS) Mensuration 3D

The sum of length, breadth and height of a room is 19m. The length of the diagonal is 11m. Find he cost of painting the total surface area of the room at the rate of `10 per m².

240

2400

360

3600

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Explanation:

Let length, breadth and height of the room be l, b and h, respectively. Then,
l + b + h = 19 … (i)
and √(l²+b²+h²)=11
⇒l²+b²+h²=121 … (ii)
Area of the surface to be painted
=2(lb+bh+hl)
(l+b+h)²=l²+b²+h²+2(lb+bh+hl)
⇒2(lb+bh+hl)=(19)²-121=361-121=240
Surface area of the room = 240m²
Cost of painting the required area = 10 × 240 = `2400