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.
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?
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).
D Priya said:
8 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.
Ramya said:
8 years ago
How to calculate cube root of 216?
Arya said:
1 decade ago
Why we need that 3^2+4^2+5^2?
Imran said:
1 decade ago
How required ratio come?
Nikita said:
8 years ago
How 216 came, can anyone explain me in simple trick?
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?
Raghavi said:
9 years ago
I too can't understand this problem. Someone explains me.
Patty said:
9 years ago
Really I don't know, how to calculate the answer. Please anyone help me.
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