Aptitude - Volume and Surface Area - Discussion
Discussion Forum : Volume and Surface Area - General Questions (Q.No. 12)
12.
A cistern of capacity 8000 litres measures externally 3.3 m by 2.6 m by 1.1 m and its walls are 5 cm thick. The thickness of the bottom is:
Answer: Option
Explanation:
Let the thickness of the bottom be x cm.
Then, [(330 - 10) x (260 - 10) x (110 - x)] = 8000 x 1000
320 x 250 x (110 - x) = 8000 x 1000
| (110 - x) = |
8000 x 1000 | = 100 |
| 320 x 250 |
x = 10 cm = 1 dm.
Discussion:
49 comments Page 5 of 5.
Saru said:
7 years ago
I am not clear with subtracting 10 cm instead of 5 cm. Can anyone help me to getting this?
(2)
Onkar said:
7 years ago
Why subtracting 10cm?
Why not 5?
Why not 5?
(2)
Rehan said:
6 years ago
@All.
When they mention the thickness of walls as 5 cm, it can also mean the bottom, isn't it?
The bottom can also have the same thickness in that sense, right?
When they mention the thickness of walls as 5 cm, it can also mean the bottom, isn't it?
The bottom can also have the same thickness in that sense, right?
Mahek said:
6 years ago
@Rehan.
They have given thickness of walls only not the bottom, so the thickness of the bottom may or may not be equal to the wall.
They have given thickness of walls only not the bottom, so the thickness of the bottom may or may not be equal to the wall.
Akshau said:
6 years ago
dm means decameter.
10cm=1 decameter.
10cm=1 decameter.
Rahul said:
4 years ago
How we get 10 multiples of each breadth depth and length? Please explain.
Ali said:
3 years ago
Why we should take 3.3 as length? Please explain me.
Khan said:
3 years ago
10cm = (10/100)m = 0.1m = 1decimeter or 1 dm.
(1)
Ujjwal Thakur said:
2 years ago
@All.
Here is the explanation for all who are not getting why 10 is subtracted.
3.3m = 330cm, which is the length of the rectangular opposite faces of the cistern. Now the wall is present on both (opposite) sides whose thickness is 5cm.
So internal length (which is being calculated to compare with capacity) will be 330-5-5 cm
Similarly for internal breadth, external breadth - thickness of both opposite walls, that is, 260cm - 5cm(thickness of 1st wall) - 5cm(thickness of the opposite wall).
So, internal breadth = 260 - 5 - 5.
The bottom thickness isn't given so we considered it as x.
Also, there's no information about the top face, so we don't have to take its thickness into consideration(negligible) or assume that the cistern is open.
Here is the explanation for all who are not getting why 10 is subtracted.
3.3m = 330cm, which is the length of the rectangular opposite faces of the cistern. Now the wall is present on both (opposite) sides whose thickness is 5cm.
So internal length (which is being calculated to compare with capacity) will be 330-5-5 cm
Similarly for internal breadth, external breadth - thickness of both opposite walls, that is, 260cm - 5cm(thickness of 1st wall) - 5cm(thickness of the opposite wall).
So, internal breadth = 260 - 5 - 5.
The bottom thickness isn't given so we considered it as x.
Also, there's no information about the top face, so we don't have to take its thickness into consideration(negligible) or assume that the cistern is open.
(13)
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