Quantitative Aptitude Ques 2370
Question: Three solid iron cubes of edges 4 cm, 5 cm and 6 cm are melted together to make a new cube. $ 62cm^{3} $ of the melted material is lost due to improper handling. The area (in $ cm^{2} $ ) of the whole surface of the newly formed cube is
Options:
A) 125
B) 216
C) 294
D) 343
Show Answer
Answer:
Correct Answer: C
Solution:
- Let edge of the new cube be a cm. According to the question, Volume of three small cubes $ -,62= $ Volume of big cube
$ \Rightarrow $ $ 4^{3}+5^{3}+6^{3}-62=a^{3} $
$ \Rightarrow $ $ a^{3}=64+125+216-62 $
$ \Rightarrow $ $ a^{3}=343 $
$ \Rightarrow $ $ a=7cm $
$ \therefore $ The whole surface area of newly formed cube $ =6a^{2}=6\times 49=294,cm^{2} $
BETA
