Aptitude - Volume and Surface Area - Discussion
Discussion Forum : Volume and Surface Area - General Questions (Q.No. 9)
9.
A cistern 6m long and 4 m wide contains water up to a depth of 1 m 25 cm. The total area of the wet surface is:
Answer: Option
Explanation:
| Area of the wet surface | = [2(lb + bh + lh) - lb] |
| = 2(bh + lh) + lb | |
| = [2 (4 x 1.25 + 6 x 1.25) + 6 x 4] m2 | |
| = 49 m2. |
Discussion:
40 comments Page 1 of 4.
Kishan said:
5 years ago
@All.
2(lb+ lh+ bh) gives the total surface area, which includes 4 walls, ceiling and floor. If we are asked the area of a wet surface, only the walls will be wet, and the floor. Ceiling won't be wet, so we need to subtract ceiling's area from the total surface area i.e. L*B
Therefore 2(lb + bh + lh) - lb.
2(lb+ lh+ bh) gives the total surface area, which includes 4 walls, ceiling and floor. If we are asked the area of a wet surface, only the walls will be wet, and the floor. Ceiling won't be wet, so we need to subtract ceiling's area from the total surface area i.e. L*B
Therefore 2(lb + bh + lh) - lb.
(40)
Mohammad Asif said:
3 years ago
@All.
It should be clearly given that tha water filling height is measured from top or bottom of the container.
Am I right?
It should be clearly given that tha water filling height is measured from top or bottom of the container.
Am I right?
(8)
Mubarak said:
8 years ago
We have 5 wet sides i.e., complete bottom portion (6mx4m = 24m2) and four walls.
Area of 4 walls = perimeter*height.
= 2(6+4)*1.25.
= 20*1.25 =25.
So total wet area = 24+25 = 49 cub.mtr.
Area of 4 walls = perimeter*height.
= 2(6+4)*1.25.
= 20*1.25 =25.
So total wet area = 24+25 = 49 cub.mtr.
(5)
Kanna29 said:
3 years ago
@All.
Here, The uppermost surface also has some specific height. Then why everyone not considering it , just multiple l*b and not h?
Here, The uppermost surface also has some specific height. Then why everyone not considering it , just multiple l*b and not h?
(2)
Shenga said:
6 years ago
See @nitya's answer.
(2)
Vicky said:
7 years ago
Good explanation, thanks all.
(1)
Sanjana said:
8 years ago
Please explain the formula 2lh+2bh+lb.
(1)
Ankit rai said:
8 years ago
But only the wet area is taken as cuboid so why do we subtract lb?
(1)
Piyush said:
10 years ago
How do we know upper part not containing height?
(1)
Vyom sharma said:
9 years ago
The side walls are also not fully wet, as everybody said that the tank is not fully filled with water.
We don't know the total height of cistern, we just know how much depth of water is cistern containing.
Then, the area of side walls must NOT be fully included as a wet area.
Then How we conclude this?
We don't know the total height of cistern, we just know how much depth of water is cistern containing.
Then, the area of side walls must NOT be fully included as a wet area.
Then How we conclude this?
(1)
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