Aptitude - Volume and Surface Area - Discussion
Discussion Forum : Volume and Surface Area - General Questions (Q.No. 3)
3.
A hall is 15 m long and 12 m broad. If the sum of the areas of the floor and the ceiling is equal to the sum of the areas of four walls, the volume of the hall is:
Answer: Option
Explanation:
2(15 + 12) x h = 2(15 x 12)
 h = |
180 | m = | 20 | m. |
| 27 | 3 |
 Volume = |
 |
15 x 12 x | 20 |  m3 |
= 1200 m3. |
| 3 |
Video Explanation: https://youtu.be/V8EQ1YIaH74
Discussion:
75 comments Page 6 of 8.
Ann said:
10 years ago
Did not understand any of this at all, sorry.
Anju b s said:
1 decade ago
It is right because it is the curved surface area of cuboid.
Anju bs said:
1 decade ago
Yes it is right because it is the curved surface area of the cuboid.
Sravanthi said:
1 decade ago
@Sonu.
It's lh not lb in your explanation.
i.e Yes the surface area of cuboid is 2 (lb+bh+hl).
But surface area of 4 walls does not includes areas of floor+ceiling.
That's why total area of walls = 2(lb+bh+bl) - 2 (lb) = 2(hb+lh) = 2 (b+l)h.
It's lh not lb in your explanation.
i.e Yes the surface area of cuboid is 2 (lb+bh+hl).
But surface area of 4 walls does not includes areas of floor+ceiling.
That's why total area of walls = 2(lb+bh+bl) - 2 (lb) = 2(hb+lh) = 2 (b+l)h.
Nameera khan said:
1 decade ago
But I did not get the starting explanation.
Chinmaysethi said:
1 decade ago
What is the formula for calculating the area of 4 walls? Is it root l square +b square+ h square?
Tejasvi said:
1 decade ago
I am unable to know the meaning of the question.
Mukesh bajaj said:
1 decade ago
It's not the surface area of cuboid brother, here it codes,
We have,
Area of ceiling + ground = area of 4 walls.
( l*b)+(l*b) = (l*h)+(b*h)+(l*h)+(b*h).
L.H.S = 2(l*h)+2(b*h).
2(l*b) = 2h(l+b).
We have,
Area of ceiling + ground = area of 4 walls.
( l*b)+(l*b) = (l*h)+(b*h)+(l*h)+(b*h).
L.H.S = 2(l*h)+2(b*h).
2(l*b) = 2h(l+b).
Ashwini pujary said:
1 decade ago
Why but we are using different formula will you explain how does 2(b+l)h has been executed?
Karthik said:
1 decade ago
Thanks sonu.
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