Aptitude - Volume and Surface Area - Discussion
Discussion Forum : Volume and Surface Area - General Questions (Q.No. 14)
14.
A large cube is formed from the material obtained by melting three smaller cubes of 3, 4 and 5 cm side. What is the ratio of the total surface areas of the smaller cubes and the large cube?
Answer: Option
Explanation:
Volume of the large cube = (33 + 43 + 53) = 216 cm3.
Let the edge of the large cube be a.
So, a3 = 216 
a = 6 cm.
 Required ratio = |
 |
6 x (32 + 42 + 52) |  |
= | 50 | = 25 : 18. |
| 6 x 62 | 36 |
Discussion:
24 comments Page 2 of 3.
MAD MATHS said:
8 years ago
Well the question says "A large cube is formed from the material obtained by melting three smaller CUBES of 3, 4 and 5 cm side. How can be a cubes sides will be different?
Nikita said:
8 years ago
How 216 came, can anyone explain me in simple trick?
Hrushi said:
8 years ago
Nice explanation @Hary.
(1)
Tuhin said:
8 years ago
I can't understand it. Someone, please explain it.
Ramya said:
8 years ago
How to calculate cube root of 216?
D Priya said:
7 years ago
216 = 2*108.
= 2*2*54
= 2*2*2*27
= 2*2*2*3*9
= 2*2*2*3*3*3
=2^3 * 3^3 = 6^3.
= 2*3= 6.
i.e 6^3 = 216.
= 2*2*54
= 2*2*2*27
= 2*2*2*3*9
= 2*2*2*3*3*3
=2^3 * 3^3 = 6^3.
= 2*3= 6.
i.e 6^3 = 216.
Vinod kumar said:
7 years ago
If you get it as it is a cube of 6 fine or else take LCM of 216 there you will get as it is a cube of 6.
After that;
a^3=6^3.
Cube roots get cancelled then a=6.
Or
a=3^216
=3^(6)^3
=(6^3)^1/3
=6 (powers get cancelled).
After that;
a^3=6^3.
Cube roots get cancelled then a=6.
Or
a=3^216
=3^(6)^3
=(6^3)^1/3
=6 (powers get cancelled).
Roshan said:
7 years ago
Why the total surface areas of smaller cubes are taken as 6* (3*3+4*4+5*5) and why not as sum of individual surface areas of smaller cubes?
Swar said:
6 years ago
I don't know why the surface area of a small cube is more than a large cube?
In question they said that large cube is made by melting 3 small cubes, so the surface area of the large cube must be 3times small cube. But why they didn't do that? Can any one answer this?
In question they said that large cube is made by melting 3 small cubes, so the surface area of the large cube must be 3times small cube. But why they didn't do that? Can any one answer this?
Mithilesh kumar pandey said:
6 years ago
Total surface area of cube is 6 a^2.
So that 6* (3*3+4*4+5*5) is written .
So that 6* (3*3+4*4+5*5) is written .
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers