Two cubes have their volumes in the ratio 1 : 27. Find the ratio of their surface areas. Choose the correct choice from the following answers
A) 1 : 9
B) 2 : 9
C) 3 : 9
D) 5 : 9
E) none of them

Rationale: let their edges be a and b . then , = a ^ 3 / b ^ 3 = 1 / 27 ( or ) ( a / b ) ^ 3 = ( 1 / 3 ) 3 ( or ) ( a / b ) = ( 1 / 3 ) . therefore , ratio of their surface area = 6 a ^ 2 / 6 b ^ 2 = a ^ 2 / b ^ 2 = ( a / b ) ^ 2 = 1 / 9 , i . e . 1 : 9 . answer is a .
Answer: A