1.  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?
A. 2 : 1
B. 3 : 2
C. 25 : 18
D. 27 : 20

Answer: Option C

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
6 x 62 36

= 25 : 18.